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Al2014–Alumina Aerospace Composites: Particle Size Impacts on Microstructure, Mechanical, Fractography, and Wear Characteristics
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  • Bharath Vedashantha Murthy
    Bharath Vedashantha Murthy
    Department of Mechanical Engineering, RNS Institute of Technology, Visvesvaraya Technological University, Bengaluru 560098, Karnataka, India
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    Orcidhttps://orcid.org/0000-0001-6765-4728
  • Virupaxi Auradi*
    Virupaxi Auradi
    Department of Mechanical Engineering, Siddaganga Institute of Technology, Visvesvaraya Technological University, Tumakuru 572103, Karnataka, India
    *Email: [email protected]
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    Orcidhttps://orcid.org/0000-0001-6549-6340
  • Madeva Nagaral*
    Madeva Nagaral
    Aircraft Research and Design Centre, HAL, Bengaluru 560037, Karnataka, India
    *Email: [email protected]
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    Orcidhttps://orcid.org/0000-0002-8248-7603
  • Manjunath Vatnalmath
    Manjunath Vatnalmath
    Department of Mechanical Engineering, Siddaganga Institute of Technology, Visvesvaraya Technological University, Tumakuru 572103, Karnataka, India
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    Orcidhttps://orcid.org/0000-0003-3138-9453
  • Nagaraj Namdev
    Nagaraj Namdev
    Department of Mechanical Engineering, APS Polytechnic, Bengaluru 560082, Karnataka, India
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  • Chandrashekar Anjinappa
    Chandrashekar Anjinappa
    Department of Mechanical Engineering, Bangalore Institute of Technology, Bengaluru 560004, Karnataka, India
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  • Shanawaz Patil
    Shanawaz Patil
    Department of Mechanical, School of Engineering, REVA University, Bengaluru 560063, Karnataka, India
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  • Abdul Razak*
    Abdul Razak
    Department of Mechanical Engineering, P. A. College of Engineering (Affiliated to Visvesvaraya Technological University, Belagavi), Mangaluru 574153, Karnataka, India
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    Orcidhttps://orcid.org/0000-0001-7985-2502
  • Abdullah H. Alsabhan
    Abdullah H. Alsabhan
    Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia
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    Shamshad Alam
    Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia
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    Mohammad Obaid Qamar
    Department of Civil Engineering (Environmental Science & Engineering), Yeungnam University, Gyeongsan 38541, South Korea
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ACS Omega

Cite this: ACS Omega 2023, 8, 14, 13444–13455
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https://doi.org/10.1021/acsomega.3c01163
Published March 27, 2023

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Abstract

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An Al2014–alumina (Al2O3) composite’s characteristics are significantly influenced by the reinforcement particle size variation. Therefore, this study examines the microstructure, mechanical, fractography, and wear performance of an Al2014–Al2O3p composite made using a unique two-stage stir casting method and various alumina weight fractions (9, 12, and 15 wt %). Three categories of alumina particle size are used, i.e., fine particle size (FPS, 8 μm), intermediate particle size (IPS, 53 μm), and coarse particle size (CPS, 88 μm). The shapes of the composites were characterized using scanning electron microscopy. According to scanning electron microscopic analyses of the microstructure, the FPS dispersion was more uniform than IPS and CPS, whereas CPS causes agglomeration. Additionally, the studies show that the FPS composite outperformed CPS and IPS composites in terms of mechanical characteristics and wear performance. The fractography study shows conical and equiaxed dimple failure in the Al2014 matrix and the circular cavities.

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1. Introduction

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Composites are mixtures of two or more chemically or physically distinct materials that have varying physical or chemical properties. (1) Composites are employed for thermal, tribological, and other purposes. (2,3) Matrix and reinforcement classify composites. Matrixes are metallic, polymer, and ceramic, and reinforcements are fiber, particle, and structural. (1)
Metal matrix composites incorporate hard ceramic particles into the matrix to increase hardness, yield strength (YS), and ultimate tensile strength (UTS). (4,5) Aluminum metal matrix composites are strengthened using discontinuous reinforcements, which improve their physical and mechanical qualities. (6) Aluminum alloys are utilized in engineering because of their ductility, corrosion resistance, strength-to-weight ratio, and low cost. (7) Aluminum alloys are wrought, cast, and heat treatable. (8) Hot and cold working processes distort aluminum into wrought products.
A wrought Al2XXX alloy, i.e., Al2014, is made by combining copper and aluminum. Adding copper to a material decreases its ductility, enhances its strength, and accelerates precipitation hardening. (9) The Al2014 alloy was selected for this investigation because of its high strength, high mechanical quality, wide range of applications, and ability to be cast. (10,11) Traditional aluminum alloys are soft and low-wearing, limiting their usefulness. Adding hard ceramic reinforcing particles to aluminum and related alloys creates a DRMMC (discontinuous reinforced metal matrix composite) with almost isotropic characteristics.
There has been much attention paid in recent years to ceramic-particle-containing metal matrix composites based on aluminum. Aluminum alloys have a wide range of ceramics: silicon carbide, (12−18) boron carbide, (13) alumina, (14) titanium carbide, (13−15) and graphite (16) have been reinforced into it in several forms such as particulates, whiskers, or fibers (17) that can be used due to their low density, melting temperature, high specific strength, and thermal conductivity. They can be adjusted to have better qualities than monolithic alloys, such as high specific strength and stiffness, higher wear resistance, and stronger thermal and mechanical fatigue and creep resistance. Researchers have found issues with metal matrix composites due to nonhomogeneous reinforcing particle dispersion. (19−21)
Powder metallurgy, (22) liquid metal infiltration, (23) and squeeze-exhausted casting (24) are all methods that have been used to create aluminum metal matrix composites using microsized ceramic particles. Stir casting is the most advantageous method for fabricating aluminum alloy matrix composites with discontinuous reinforcement because of its good matrix-reinforcing particle adhesion, simplified matrix structure regulations, ease of manufacturing and cost effectiveness, closer net shape, and high production rates (in terms of higher weight fraction). (25)
Stir casting incorporates ceramic particles into a molten matrix in one stage. (26,27) In the current study, Al2014–Al2O3 composites are created using two-stage stir casting in which reinforcing particles are introduced in two-stages. This two-stage mixing improves the wettability of the matrix’s reinforcing alumina. (28) Improving wettability and casting improves aluminum matrix composite characteristics.
Many researchers have evaluated the characteristics of Al2O3, TiC, B4C, SiC, graphite, and fly ash composites. (29−35) Sekar (36) described A356 and Al2O3 composites. Al2024 and Al2O3 particle-reinforced composites with varied particle size, (37) density, hardness, and tensile strength were investigated. Al2014 and Al2124 alloys were reinforced with different particle sizes of Al2O3, (38) as well as Al6061–Al2O3, (39) Al2024–ZrB2, (40) Al6061–B4C, (29) Al2219–TiC, (41) and Al5083–TiB2 (42) composites. Reduced particle size improves composite strength. (43)
The aluminum matrix composite concept can be extended. Currently, mechanical and wear attributes are driving metal matrix composite development. Mechanical and wear property improvements are still crucial. Further advancements in this area include reinforcing rapidly solidified matrices to provide strength and combining discontinuous and continuous matrix reinforcements to add strength and optimize mechanical and wear qualities. These issues require extensive laboratory research.
Several groups of researchers have applied various matrix and reinforcement processing techniques to metal matrix composites. Liquid and powder metallurgy (41,44,45) are used to treat metal matrix composites. Despite their best efforts, it is difficult to incorporate soft or hard nonmetal or ceramic reinforcements into aluminum alloy. An enhanced method is needed to enhance wetting and particle uniformity in aluminum-based metal matrix composites.
Few researchers have studied how particle size reinforcement affects mechanical and wear parameters of Al2014 alloy reinforced with Al2O3p composite manufactured by a unique two-stage liquid stirring technique. Al-based composites are being explored as candidates to replace steel or aluminum alloys in potential modern applications. Cylinder liners and brake rotors are classic examples. An Al2014 alloy reinforced with Al2O3 composite is employed in aircraft and motor sectors, mainly in the fabrication of structural frames (i.e., bulk head and fork hinge of rudder). New formulations and property evaluations are needed. This study investigates the influence of particle size variations (FPS, IPS, and CPS) on mechanical and wear behavior of Al2014–Al2O3p composites with varied weight fractions.

2. Fabrication Procedure

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2.1. Matrix and Microparticulate Reinforcement: The Particulars

In the present study, Al2014 and Al2O3 are used as the matrix (Supplier: Fenfee Metallurgical Bangalore, India) and reinforcement. The chemical composition of Al2014 is shown in Table 1.
Table 1. Al2014 Chemical Composition in % by Weight
elementsMgSiFeCuTiCrZnMnAl
Al2014 (actual, wt %)0.630.70.24.50.060.010.190.83balance

2.2. Al2014–Al2O3 Metal Matrix Composite Synthesis

The current investigations examined the preparation of Al2014 reinforced with 9 wt % Al2O3 (CPS, 88 μm) metal matrix composites utilizing the most common and cost-effective liquid metallurgical method: the stir casting process. First, a Gr crucible containing a measured quantity of Al2014 alloy was heated to 725 °C in an electrical resistance furnace. A 9 wt % weighted quantity of reheated Al2O3 was injected into the melt in two stages to prevent segregation and enhance the dispersion of the particles throughout the alloy matrix. Once this temperature was reached, hexachloroethane (C2Cl6) was added to prevent gas entrapment during stirring. Intense mixing was achieved with a zirconia-coated steel impeller and a constant speed of 250 rpm for 10 min. Later, a 125 mm × 12.5 mm × 12.5 mm mold was created, and the melt was transferred into it. After cooling, the Al2O3 metal matrix composites took on a cylinder shape. The same procedure was followed for the preparation of the composites with different weight fractions (12 and 15 wt %) with varied particle sizes (IPS 53 μm and FPS 20 μm).

2.3. Experimental Details

In order to produce the test samples required by ASTM, the obtained Al2014–9, −12 and −15 wt % Al2O3 metal matrix composites were machined. Using a Vickers hardness tester manufactured by Zwick/Roell Indtech (ZHV) in Germany, the microhardness of the highly polished cast Al2014 and Al2014–9, −12 and −15 wt % Al2O3 metal matrix composites with variable particle sizes was measured in accordance with ASTM E10. The specimen was 15 mm in diameter and 10 mm in length, and tests were run with a load of 300 g (HV 0.3) distributed over its surface for 10 s. In order to check the potential effects of indenter laying on harder particles, the investigation was conducted at ten different locations. The sample’s hardness was determined by averaging the results of ten separate readings. ASTM E8 ultimate tensile strength tests were conducted on an INSTRON-5980 model of a computerized universal testing machine (UTM) built in the USA, which has a maximum capacity of 60 kN and a minimum count of 4 N. At a speed of 0.1 mm/min, displacement mode was used for all testing. There were three separate trials conducted, and the mean value was stated. Matrix and composite tensile behaviors, including UTS, YS, and ductility, were evaluated. The fracture surfaces were displayed using SEM to identify the mechanism of fracture for the microstructural studies. The wear behavior of the materials was examined by conducting wear tests. Produced composite samples were subjected to dry sliding wear testing using a computerized pin-on-disk tribometer from DUCOM Instruments Pvt. Ltd., Bangalore, India (35,36) (Model: TR20LE). The wear testing machine had a counter disc made of EN-32 steel that was HRC65 hard and had a maximum track diameter of 160 mm. The tests were performed on cylindrical samples that were 8 mm in diameter and 25 mm in height. The wear behavior of the composites under diverse conditions was studied in the present work. In the wear testing, variables like load (N) and sliding distance (m) were used. Optical investigations were performed to determine the major wear mechanism by observing the wear and debris on the as-cast and composite test samples, each of which contained particles of varying sizes. Scanning electron microscopy with a TESCAN VEGA 3 from LMU in the Czech Republic was used to examine the composites’ microstructure (SEM). Worn areas and fractured samples were scanned using a SEM for analysis of the wear and fracture.

3. Results and Discussions

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3.1. Microstructural Characterization of Alumina Reinforced Al2014 Composites with Different Weight Fractions

SEM images of Al2014–Al2O3p (9, 12, and 15 wt %) reinforced composites with different particle sizes (CPS 88 μm, IPS 53 μm, and FPS 20 μm) that were synthesized by stir casting are shown in Figure 1a–j. In the composite microstructure, alumina particles are separated between eutectic silicon and primary α-Al dendrites. Changing the dendrite-shape into an equiaxed structure by stirring the melt at 250 rpm while adding preheated alumina particles in two phases improves the wettability and integration of alumina particles in the liquid and disperses them more uniformly throughout the matrix. Figure 1b–d illustrates the distribution of alumina particles CPS 88 μm in composites with varying weight percentages. As the amount of alumina (wt %) increases, the alumina particles continue to separate and form clusters enriched in eutectic silicon in interdendritic regions at very few locations, primarily as a result of optimization of processing parameters during stir casting.

Figure 1

Figure 1. (a–d) SEM images of Al2014–Al2O3p composites with different composition of CPS (83 μm) alumina particulates: (a) as-cast Al2014 alloy, (b) Al2014–9 wt % Al2O3p, (c) Al2014–12 wt % Al2O3p, and (d) Al2014–15 wt % Al2O3p. (e–g) SEM images of Al2014–Al2O3p composites with a different composition of IPS (53 μm) alumina particulates: (e) Al2014–9 wt % Al2O3p, (f) Al2014–12 wt % Al2O3p, and (g) Al2014–15 wt % Al2O3p. (h–j) SEM images of Al2014–Al2O3p composites with different compositions of FPS (20 μm) alumina particulates: (h) Al2014–9 wt % Al2O3p, (i) Al2014–12 wt % Al2O3p, and (j) Al2014–15 wt % Al2O3p.

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Figure 1b–d illustrates that the grain size of the reinforced composite is less than that of the base alloy without alumina particles (Figure 1a). As the mixture solidifies, the alumina particles added to the molten metal frequently act as heterogeneous nucleation sites.
Figure 1e–g shows the composite reinforced with IPS (53 μm) with different weight fractions. In higher-weight fractions of alumina (12 and 15%) Al2014 composites (Figure 1e–g), regions in which an enormous number of particles were in contact were frequently observed because of the introduction of two-stage mixing of preheated (250 °C) alumina particles into the melt and keeping the uniform stirring speed (250 rpm), uniform stirring time (10 min), and constant pouring temperature (750 °C).
Optimized stirring time (10 min) and speed (250 rpm) leads to stronger dissemination of particles (Figure 1e–g), and if the stirring speed (>250 rpm) and time (>10 min) increases, it may cause the chemical reactions with the particles and matrix which leads to the formation of brittle secondary phases. (46,47) Hence, in the present work the stirring speed and time is optimized to 250 rpm and 10 min, respectively, to achieve consistent dissemination of the strengthened alumina particles. Further, much less agglomeration is found in the composite containing 15 wt % of Al2O3 particles, and good bonding is seen between the matrix and reinforcement (Figure 1g); this is because of implementing the optimized processing parameters in casting as mentioned above.
Figure 1h–j depict the electron microscopic images of composites reinforced with a FPS alumina (20 μm) with different weight fractions. Figure 1i,j depicts a much smaller quantity of interdendritic stage that leads to eutectic solidification. It can be seen that the matrix is well bonded with the reinforced particulates. Dendritic fracture can be related to the stirring action shearing the starting dendritic arms; i.e., vigorous stirring is carried out at 250 rpm about 10 min. The mechanical stirring disperses the particles consistently as well as reduces the settling of the particles during the solidification. Local solidification takes place due to the variations in the temperature between the particle and the melt during the addition of the particles. Finally, synthesized composite shows uniform and homogeneous dispersion of FPS (20 μm) particles within the alloy matrix depicted in Figure 1i,j.
Excellent bonding exists with the reinforced alumina particle and alloy matrix as is shown in Figure 1j, and this is because of the implementation of the optimized processing parameters. The strong interface offers excellent mechanical and tribological properties, as the transmission of the load happens via the interface. (48) The existence of hard ceramic particles which limit dendrite development and change the matrix with a progressively refined structure results in improving the strength. (49−53)Figure 1j depicts the existence of dendrites in places far away from the particle. The cumulative examination of the microstructure (Figure 1h–j) demonstrates that the gaps/interspaces between the reinforcements decrease in the matrix as the weight fraction of the reinforcement increases. This may additionally impede the movement of a dislocation. Hence alumina can probably stop the movement of dislocations in the Al2014 matrix. Therefore, the tribological property of the composites may improve.

3.2. Hardness Measurement

Figure 2 shows how particle size affects composite microhardness at different alumina weight percentages. Composite hardness improved by 5.50 (104.45 ± 3.26 HV 0.3), 13.17 (112.04 ± 3.82 HV 0.3), and (118.01 ± 4.50 HV 0.3) 19.20% for CPS (88 μm); 16.82 (115.66 ± 4.66 HV 0.3), 22.33 (121.11 ± 3.02 HV 0.3), and 29.43 (128.14 ± 3.97 HV 0.3) for IPS (53 μm); and 25.47 (124.22 ± 2.42 HV 0.3), 33.41 (132.08 ± 2.46 HV 0.3), and 45.55 (144.10 ± 2.06 HV 0.3) for FPS (20 μm) alumina particles compared to Al2014 alloy (99 HV 0.3). The presence of alumina is primarily responsible for the increase in matrix hardness. (54)

Figure 2

Figure 2. Particle size impact on microhardness measurements of base alloy and produced composites with variable particle size and weight fractions.

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In Figure 2, decreasing particle size increases reinforced composite hardness. This has various causes. First, the FPS (20 μm) interface is greater than that of the IPS and CPS (53 and 88 μm) reinforced particles, which increases hardness. Second, smaller particles have more surface area than CPS (88 μm) particles in composites.
Third, considering that dissemination of the particle size is similar in all instances, the distance between finer particles is shorter than that between the IPS (53 μm) and CPS. As a result, the composite reinforced with FPS has more impact in preventing dislocation movement when pressure is being applied by the hardness system indicator. Therefore, maximum hardness value is obtained.

3.3. Evaluation of Mechanical Properties

Figure 3a shows how particle size affects composite UTS at different alumina weight percentages. In Figure 3a, decreasing particle size and increasing alumina weight percentage increases composite tensile strength. This is in agreement with other research. (55,56) In addition, fairly uniform dissemination (dispersion) of FPS (20 μm) alumina particles as confirmed by SEM micrographs (as all ready depicted in Figure 1h–j) in FPS alumina reinforced composites as compared to the composites reinforced with IPS and CPS (53 and 88 μm) affects the tensile strength of the composites produced with varying the weight percentages. The UTS of the composites improved by 12.46% (167.90 ± 4.14 MPa), 16.29% (173.61 ± 3.55 MPa), and 29.59% (193.47 ± 2.87 MPa) for CPS (88 μm); 23.71% (184.69 ± 4.46 MPa), 38.48% (206.75 ± 4.88 MPa), and 51.46% (226.12 ± 4.86 MPa) for IPS (53 μm); and 33.17% (198.81 ± 4.36 MPa), 49.70% (223.49 ± 2.22 MPa), and 59.78% (238.54 ± 4.16 MPa) for FPS (20 μm) alumina particles, compared to Al2014 alloy (149.29 MPa).

Figure 3

Figure 3. (a) UTS, (b) YS, and (c) percentage elongation of base alloy and produced composites with variable particle size (FPS, IPS, and CPS) of alumina at different compositions (9, 12, and 15 wt %)

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The composite produced (Al2014–15 wt % of Al2O3p) with FPS (20 μm) has the maximum tensile strength in comparison to Al2014 base alloy and composites with varied compositions and particle sizes (IPS and CPS). The matrix and particles may be atomically cohesive. This suggests that the matrix and FPS (20 μm) particles are in intimate contact. (56)
The impact of particle size on the YS of composites generated at various alumina weight percentages is depicted in Figure 3b. As shown in Figure 3b, the yield strength of the generated composites increases as the size of the particle lowers and the weight fraction of the alumina increases. The alumina high strength protects the alloy matrix which is relatively fragile. The yield strength (0.2% offset) of base material is 138.01 ± 4.19 MPa while the maximum yield strength of 201.29 ± 3.56 MPa for 15 wt % of alumina particles with a size of 20 μm is observed. Clearly, more load can be transferred to reinforcement with an increase in weight percentage, resulting in maximum yield strength. Therefore, the key point is that the increase of the yield strength of the synthesized composite increases as the particle size decreases (Figure 3b). This is in line with other investigations. (55,56) The degree of improvement in the YS of the synthesized composites is about 5.45% (145.54 ± 3.40 MPa), 12.46% (155.21 ± 3.86 MPa), and 29.54% (178.78 ± 3.57 MPa) for CPS (88 μm); 24.06% (171.22 ± 3.21 MPa), 35.00% (186.32 ± 2.81 MPa), and 40.66% (194.13 ± 2.60 MPa) for IPS (53 μm); and 33.75% (184.60 ± 2.94 MPa), 42.09% (196.11 ± 2.96 MPa), and 45.85% (201.29 ± 3.56 MPa) for FPS (20 μm) alumina particles as contrasted to Al2014 alloy.
The effects of particle size on the percent elongation of composites generated at various alumina weight percentages are shown in Figure 3c. As shown in Figure 3c, increasing the weight percentage of alumina causes a reduction in the percentage elongation of the generated composites as the particle size decreases. Kok has a comparable observation. (37) As compared to the composites made using CPS and IPS (88, 53 μm) and the as-cast Al2014 alloy matrix, the composite generated with 15 wt % FPS (20 μm) exhibits less elongation in the current experiment. The decrease in ductility may also be directly related to a large refined microstructure, homogeneous distribution of reinforcing particles, and a decrease in porosity. All these variables together strengthen the matrix and composites interfacial strength and ductility. (57) These factors have been accomplished in the present studies by selecting the optimized parameters.

3.4. Fracture Behavior

At various magnifications, Figure 4a–h shows the cracked surfaces of both as-cast Al2014 alloy and Al2014–15 wt % alumina particles with CPS, IPS, and FPS (88, 53, and 20 μm). The objective of the tensile fracture is to determine the effect of variation in the size particle on the fracture behavior of composites with maximal weight fractions. The most significant weight fraction of composites with different particle size is selected in the present work for the study of fractured surface due to enhanced uniform dispersion of the reinforcing particulates in the matrix (Al2014) alloy and enriched mechanical properties such as microhardness, UTS, YS, and good ductility is accomplished with 15 wt % alumina particulate composites (as discussed in the earlier sections) as compared to the 9 and 12 wt % of alumina particulates. Failure of particle-reinforced AMCs is caused by interface decohesion between the matrix and reinforcement, fracture of reinforcement, and matrix failure.

Figure 4

Figure 4. (a–h) Fractographic of images of (a, b) Al2014 and (c–h) Al2014–15 wt % Al2O3 with CPS, IPS, and FPS and at different magnifications.

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The composite (Al2014–15 wt % alumina) reinforced with CPS (88 μm) exhibits tensile fracture as shown in Figure 4c,d. Small ductile dimples are clearly evident in the matrix alloy denoted by blue circles, and particle pull-out is detected, as depicted in Figure 4d. The reinforced composites’ fracture surfaces show that the modes of fracture along the particle surface (brittle rupture) and the matrix (dimple rupture) may be distinguished clearly (Figure 4c,d). These fracture characteristics indicate a reduction in plastic deformation because of the alumina particle inclusion. (58)
Figure 4e,f demonstrates the tensile fracture behavior of the composite (Al2014–15 wt % of alumina) with IPS (53 μm). Figure 4f reveals the very small/minute dimples (except that the length scale of the dimples is different as depicted in Figure 4d) in the matrix alloy marked by red-colored circles and the size of the dimples are dependent on the size of the alumina particles. In the images (Figure 4f), hair line microcracks (shown with the arrow) of the composites with CPS (in the present study as compared to the FPS of 20 μm) appear to fracture/break. (59) The interfaces between particles and matrix stay unchanged and support the proposal that the shear strength at the interface is greater than that of the particle fracture. Kumai et al. (60) in SiC enhanced particulate Al6061 alloy also observed similar findings. Some alumina particles were also found in the dimple centers (Figure 4f), while it appears that many particles were dislodged, possibly owing to relief of residual stress. The composite reinforced with CPS (53 μm) (Figure 4e,f) reveals nearly a ductile intermediate fracture with reinforcement dimples.
Figure 4g,h illustrates the tensile fracture behavior of the composite (Al2014–15 wt % of alumina) with FPS (20 μm), while the composite displays a two-way distribution of dimples, initially bigger dimples and then smaller dimples generated by ductile matrix failure. Furthermore, electron microscopy of the fracture surfaces of composite (Figure 4g,h) revealed decohesion of the particle with the matrix and reinforcement. In the majority of cases, the particle fracture surface is smooth, indicating that the particle is fractured rather than decohered and indicating that the interface strength of these composites is high. Due to the inclusion of Al2O3p particles, the fracture behavior of Al2014 matrix shifted from ductile to brittle mode and then to intermediate ductile mode, as shown by the presence of small dimples in the matrix material. Studies on fractography clearly demonstrate a strong link between matrix and reinforcement, leading to advancement in the mechanical properties of composites as the particle size decreases. Therefore, UTS, YS, and percentage elongation findings obtained (discussed in earlier section 3.3) are reasonably appropriate and can be interconnected with fractographic studies.

3.5. Wear Behavior

3.5.1. Effect of Particle Size Variation on Load

Figure 5a depicts the wear rate results of all produced composites (i.e., with CPS, IPS, and FPS) on different loads. It is seen that (Figure 5a) the produced composite with FPS demonstrated lower volumetric wear rate at all the tested loads as compared to the IPS and CPS reinforcing alumina particulate composite and unreinforced alloy. The explanation is likely that fine reinforcing particles are strongly disseminated in the matrix as contrasted to coarse and intermediate reinforcing particles. Furthermore, the edges of fine particles are sharp and help to cut the disc on which the specimen orbits. The sharp edges of the abrading alumina become blunt during this operation. This leads to the reduction of wear. In contrast to IPS and CPS, fine particles (FPS) have sharper edges. In addition, in comparison to IPS and CPS, the sharp edge particles (i.e., FPS) can be easily placed into the matrix when the load is applied. Since, under these conditions, the intermediate and coarse particles are not easily incorporated in the matrix, they become fragmented and the wear rate increases. This indicates that a composite produced with a fine particle (FPS) is more effective as compared to the composites with IPS and CPS, and also it indicates that composite produced with fine particles exhibits better wear resistance in comparison with IPS and CPS ones as well as unreinforced alloy.

Figure 5

Figure 5. (a, b) Volumetric wear results of CPS, IPS, and FPS variations of synthesized composites (a) for different load conditions and (b) for different sliding distance conditions.

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Even so, at higher (greater) normal loads, the variation between the wear rates of the composite produced and the as-cast is important. Hence, at greater load (49.05 N), the extent of improvement in wear resistance (i.e., reduction in wear rate) of Al2014–15 wt % Al2O3p composites is about 27.30% for CPS, 55.26% for IPS, and 72.03% for FPS as compared to Al2014 matrix alloy. Therefore, it is concluded that among all the produced composites with coarse, intermediate, and fine particle, the Al2014–15 wt % Al2O3p composite with FPS exhibits higher wear resistance. This considerable enhancement in wear resistance of the Al2014–15 wt % Al2O3 composites with FPS (20 μm) can be related to the following explanation. The microhardness of the composite produced with FPS (20 μm) is improved by an increase in the level of alumina reinforcement as compare to the composites produced with 88 and 53 μm (confirmed by Figure 2). Improvement in hardness decreases the severity of wear. Extreme adhesive wear is stated to depend on the hardness of the material. (61) In addition, the experimental support and functional evidence (62) indicate that the beginning of the adhesive process, such as seizure and scuffing, is slowed down as the hardening of the metals is increased. The SEM of the worn sample of the composites produced shown in Figure 6b–d shows the strong relationship with the matrix and particles. The interfacial link with the matrix and reinforcement of the particle is of major relevance in wear operations. (63)

Figure 6

Figure 6. (a–h) Worn surface images of CPS, IPS, and FPS variation of Al2014–15 wt % Al2O3p composites. (e–h) Wear debris images of CPS, IPS and FPS variation of Al2014–15 wt % Al2O3p composites.

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In addition, a decrease in volumetric wear rate of the synthesized composite with FPS (20 μm) as compared to the composites produced with CPS or IPS (88 and 53 μm) and as-cast can also be due to greater load carrying ability and fracture strength of the alumina particles. The micrograph, on the other hand, indicates that the matrix alloy and aluminum particles have strong bonding. Therefore, development of adequate bonding decreases the risk of decohesion or pull out of reinforced phase from the matrix alloy by restricting the circumstance of three abrasive wear on the body, that would otherwise have contributed to increased removal of material.

3.5.2. Effect of Particle Size Variation on Sliding Distance

Figure 5b depicts the volumetric wear rate results of all produced composites (i.e., with CPS, IPS, and FPS) on different sliding distance. Due to the increased load-bearing capacity of the fine particle composite compared to the IPS and CPS ones, the composite generated with FPS demonstrates not only reduced wear rate but also maximum reduction in run-in wear compared to composites containing IPS and CPS. In addition, there is an increase in interfacial resistance between Al2014 matrix alloy and FPS alumina particles due to the high surface adhesion, which impedes particle separation from the Al2014 matrix. Thus, it is determined that a rise in weight percentage (9, 12, and 15 wt %) and a reducing the Al2O3p size reduces the wear rate, thereby increasing the composite’s wear resistance. This indicates that a composite produced with FPS is more effective as compared to the composites with IPS and CPS. Thus, the composite produced with FPS exhibits improved wear resistance in comparison with IPS and CPS as well as unreinforced alloy. The possible reason for increased wear strength (resistance) of the composite is the larger contact surface area of FPS in the matrix.
At greater sliding distances, the differential in wear rate between the resulting composite and as-cast is typically taken into account. Consequently, over a greater sliding distance (2000 m), the wear resistance (i.e., reduction in wear rate) of Al2014–15 wt % Al2O3p composites is around 23.88% for CPS, 55.59% for IPS, and 74.15% for FPS in comparison to the as-cast Al2014 matrix alloy. In conclusion, among all the composites made using CPS, IPS, and FPS, the Al2014–15 wt % Al2O3p composite with FPS has the highest wear resistance.

3.6. Morphological Features of the Worn Surface and Wear Debris

The wear resistance of Al2014–15 wt % alumina composites reinforced with CPS (88 μm), IPS (53 μm), and FPS (20 μm) is higher than that of Al2014–9 or −12 wt % alumina composites reinforced with CPS, IPS, and FPS, and higher than that of unreinforced Al2014 alloy. The debris morphological features and worn surface of composites (Al2014–Al2O3p) containing CPS, IPS, and FPS alumina particles at higher weight fraction (Al2014–15 wt % Al2O3) are shown in this work to aid in the determination of the probable wear mechanism.
Figure 6a–h displays the results of an SEM study of wear debris and tracks produced by Al2014–15 wt % Al2O3 composites reinforced with CPS, IPS, and FPS alumina particles over a sliding distance of 2000 m and a sliding speed of 400 rpm. Standard characteristics were seen for both Al2014 base alloy, and all composites include the formation of deep and continuous ploughing grooves and an adhesion and abrasion phenomenon in the direction of sliding.
Figure 6a depicts the worn surface images of Al2014 alloy tested under a sliding distance of 2000 m, speed of 400 rpm and a load of 49.05 N. The study of Al2014 alloy shows significant grooved patches on the worn surface. Also Al2014 alloy contains deeper adhesive grooves, cracks on the worn surface, and scratches indicating the plastic deformation of unreinforced material. It reveals continuous wear grooves and some damaged regions as shown in Figure 6a. A significant adhesive groove shows that the frictional heat (high temperature) renders the matrix soft. Highly damaged areas are also an indicator of greater material loss due to a chip out of the material at a greater load, sliding distance, and speed. The wide or bigger delaminated region reveals the predominant adhesive wear in the unreinforced Al2014 base alloy.
In the case of Al2014–15 wt % Al2O3 composites reinforced with CPS (Figure 6b), IPS (Figure 6c), and FPS (Figure 6d), the images show parallel grooves which indicate abrasive wear as formed by the intrusion of the hard alumina particle into a smooth surface. Scored grooves formed on the track disc in addition to the impact of the wear-hardened deposits. Figure 6b–d demonstrates that local damage and fractured spots are noticed at a maximum sliding distance of 2000 m, speed of 400 rpm, and load of 49.05 N.
Figure 6b, composite reinforced with CPS alumina particles, shows the existence of shallow abrasive grooves and higher delaminated area leading to a maximum wear rate, and Figure 6c, composite reinforced with IPS alumina particles, demonstrates the existence of medium size abrasive grooves and limited amount delaminated area resulting in a decreased rate of wear as compared to the composite reinforced with CPS. Figure 6d, composite reinforced with FPS alumina particles, exhibits very small grooves and smooth surface, resulting in small amount of material loss and thereby reduced wear rate to maximum extent which indicates the higher wear resistance of the FPS alumina reinforced composite as compared to the composites reinforced with IPS and CPS alumina particles, and the presence of smooth wear surface in the composite with FPS alumina particles is evident from the reduction in volumetric wear rate as compare to IPS and CPS alumina particle reinforced composites as well as as-cast Al2014 matrix alloy. The delaminated region in the composite relies on the distance between the particles in the matrix. This particle distance relies on the weight percentage of reinforcement and particle size. From the overall worn surface examination, it is observed that the Al2014–15 wt % Al2O3 composite reinforced with FPS alumina particles shows a very small amount of delaminated area and formation of grooves compared to composites (Al2014–15 wt % Al2O3) with CPS and IPS alumina particles. The possible reason for this is that particle-to-particle distance might be less in the case of composite reinforced with FPS alumina particle as compared to IPS and CPS inside the matrix. The smooth surface morphology of the composite with FPS is because of the load carrying capability and formation of an oxide layer which prevents the higher wear rate of the composites as compare to composite reinforced with IPS and CPS alumina particles.
Overall the examination of the worn surface with respect to the variable particle size composites demonstrates that, under sliding distance of 2000 m, speed of 400 rpm, and load of 49.05 N, under the ploughing operation, the protecting layer of the reinforcing coarse particles may no longer remain intact and the wear strips produced are quite distinct and interfacial strength between the coarse alumina particles and Al2014 alloy matrix is poor. Hence, the highest wear rate is observed in case of composite reinforced with CPS alumina particles.
Moreover the composite with IPS experienced lower wear rate compared to the CPS alumina particle composite. On the other hand, the composite with FPS alumina particles results in the lowest wear rate compared to CPS and IPS alumina reinforced composites due to the higher interfacial strength existing between the fine size alumina particles and the Al2014 matrix alloy. This indicates that the composite reinforced with FPS alumina results in enhanced wear resistance as contrasted to the composites with CPS and IPS alumina.
Figure 6e–h shows electron microscopy of wear debris from Al2014–15 wt % Al2O3 composites supplemented with CPS, IPS, and FPS alumina particles. The samples are tested at 400 rpm, 2000 m, and 49.05 N. As shown in Figure 6e, under the wear testing conditions, the amount of sheet- and flake-like debris increases significantly as the matrix becomes smooth, resulting in a transition from moderate to excessive wear. Repetitive sliding at greater loads caused microfractures. (64,65) At a higher load of 49.05N, sliding speed of 400 rpm, and distance of 2000 m, the matrix is softer and wears mildly to severely. This wear detritus shows that adhesive wear is mostly sliding. Metal is carved off in the shape of sheets and flakes resembling trash due to the sticky feature at increased load, speed, and sliding distance.
Figure 6f reveals the alloy matrix plate/flake-like debris and layered structure found by frequent rubbing from the pins to the counterface induced by continuous sliding. The fractured particles are bound to the delaminated debris with large scale, and also disengagement of the debris by ploughing activity is found. The resistance provided by dispersed particles shows the microcracks in the surface of the debris when the disconnected leaves are cracked in the surface. While rubbing, debris is fused with an iron disc, revealing the surface’s shearing characteristics. (66) The morphological characteristics of wear debris are found to display a higher composite wear rate. Figure 6f also shows pull-out of ductile material with thread-type structure.
Figure 6g reveals debris particles which can also be the abrasive particles of the third body and may also cause increased wear rate. The microploughing on the contact surface of the composite creates loose debris, stuck between the specimen and the counterface. The strong oxide layer (Figure 6g) encountered suggests severe symptoms of wear which rule under the above-mentioned wear testing conditions. Sheet, flake-like and crushed debris and also corrugated structure are found in the process of sliding wear (Figure 6g) because of the frequent rubbing of worn-out debris.
Figure 6h shows wear debris with a wavy pattern structure induced by microscopic particles in the matrix and plate/flake/sheet-like and round-shaped oxide (Al2O3) debris are seen in Figure 6h. Under the wear conditions stated above, the oxide layers (Al2O3/Fe2O3) rotate inside the grooves, reducing composite wear. (64,67) Many sources produce spherical wear debris, such as wear debris in surface grooves. These can also be induced by base metal, local melting, and contaminating of the air. (68) During frictional heating, these spherical types emerge at greater loads. The temperature of metallic debris is rising during the constant rubbing process. The presence of thin-wire style and spherical form debris reveals that metal threads are initially fused and develop to almost spherical shape. The smaller spherical molten debris (Figure 6h) on the surface of the bigger one is the result of the smaller molten mass adhering to the larger one. (69) The wear rate may not rise dramatically in this situation because the large adherent tribo-oxide layer is formed under greater frictional heat and the resulting increase of temperature.

4. Conclusions

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  • SEM images of produced composites with FPS, IPS, and CPS (20, 53, and 88 μm) reveal that stir casting with two-step addition of Al2O3p fairly uniformly distributes Al2O3p in the Al2014 matrix alloy. Further, increasing the weight percentage and reducing the alumina particle size in the produced composites leads to more uniform dissemination of Al2O3p.

  • Among all the produced composites, Al2014–15 wt % Al2O3p composite with FPS (20 μm particle size) results in more uniform dispersion of the particles in base matrix alloy as compared to the composites (Al2014–9, −12, and −15 wt % Al2O3) with CPS and IPS (53 and 88 μm), while the composite with IPS and CPS lead to accumulation and segregation of Al2O3p at certain locations.

  • Maximum hardness was observed for the produced composites with variable particle size compared with that of Al2014 matrix alloy due to the addition of alumina particles in the base alloy. Further, increase the weight proportion and varying the size of the alumina particles leads to maximum hardness value. Among the produced composites, the Al2014–15 wt % Al2O3p composites with FPS (20 μm) show maximum hardness value of about 144.10 VHN compared to the composites with different weight percentages (9–15 wt %) of alumina particles with sizes of 53 and 88 μm, respectively.

  • Composites produced with CPS, IPS, and FPS variable particle sizes have shown better results in UTS and YS than the Al2014 alloy. Further, the UTS and YS of the composites increases with rise in the weight proportion and decreasing size of the reinforced alumina particles. Among produced composites, the Al2014–15 wt % Al2O3p composites with FPS (20 μm) show maximum UTS and YS values as compared to the composites with different weight percentages (9–15 wt %) of alumina particles with CPS and IPS, as well as base Al2014 alloy.

  • Al2014–15 wt % Al2O3p composites with FPS (20 μm) demonstrate lower percentage elongation as compared to the composites with different weight percentages (9–15 wt %) of alumina particles with CPS and IPS, as well as as-cast Al2014 alloy (11.21%).

  • Fractography analysis of tensile fractured surfaces using SEM indicates the various fracture mechanisms of Al2014 alloy and its Al2O3 reinforced composites with a variable particle size. Al2014 alloy exhibits larger and more uniform dimples, indicating a malleable fracture, whereas the composites reinforced with CPS and IPS exhibit an almost intermediate ductile fracture, with dimples embedded on the reinforcement, and the composite reinforced with FPS exhibits ductile-to-brittle-to-intermediate-ductile transition because of the alumina particulate incorporation.

  • Composites produced with CPS, IPS, and FPS alumina demonstrate decreased volumetric wear rate as compared to the base Al2014 alloy. The volumetric wear rate of the Al2014–Al2O3p composites with different weight proportion as well as varying particle size is affected by the wear parameters such as applied load and sliding distance.

  • Examination of the worn surfaces of Al2014–15 wt % Al2O3p composites with a variable particle size using SEM clearly indicates that adhesion, delamination, abrasion, and combination of adhesion and abrasion are the principal wear processes during material exclusion on sliding.

  • Wear debris of base matrix alloy and composites (Al2014–15 wt % Al2O3p) with CPS, IPS and FPS were examined using SEM. Larger size flake and sheet like wear debris are observed in the case of Al2014 alloy than that of Al2014–15 wt % Al2O3p composites with a variable particle size. Metallic debris undergoes melting at 49.05 N load, speed of 400 rpm, and sliding distance 2000 m causing fine thread type and spherical shape debris.

Author Information

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  • Corresponding Authors
  • Authors
    • Bharath Vedashantha Murthy - Department of Mechanical Engineering, RNS Institute of Technology, Visvesvaraya Technological University, Bengaluru 560098, Karnataka, India;  Orcidhttps://orcid.org/0000-0001-6765-4728
    • Manjunath Vatnalmath - Department of Mechanical Engineering, Siddaganga Institute of Technology, Visvesvaraya Technological University, Tumakuru 572103, Karnataka, India;  Orcidhttps://orcid.org/0000-0003-3138-9453
    • Nagaraj Namdev - Department of Mechanical Engineering, APS Polytechnic, Bengaluru 560082, Karnataka, India
    • Chandrashekar Anjinappa - Department of Mechanical Engineering, Bangalore Institute of Technology, Bengaluru 560004, Karnataka, India
    • Shanawaz Patil - Department of Mechanical, School of Engineering, REVA University, Bengaluru 560063, Karnataka, India
    • Abdullah H. Alsabhan - Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia
    • Shamshad Alam - Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia
    • Mohammad Obaid Qamar - Department of Civil Engineering (Environmental Science & Engineering), Yeungnam University, Gyeongsan 38541, South Korea
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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The authors would like to acknowledge the support provided by Researchers Supporting Project Number RSP2023R473, King Saud University, Riyadh, Saudi Arabia. The authors would also like to thank Vision Group of Science and Technology, under CISEE Scheme Bengaluru, Government of Karnataka, India, for financial assistance in carrying out the research work, VGST/CISEE/GRD No: 928/2020-21/72

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    Pin-on-disk dry sliding tests were carried out to study the wear mechanisms in a range of metal-matrix composites. 6061-Aluminum alloys reinforced with 10 and 20 vol% SiC and Al2O3 particles were used as pin materials, and a mild steel disk was used as a counterface. A transition from mild wear to severe wear was found for the present composites; the wear rate increased by a factor of 102. The effects of the ceramic particles on the transition load and wear with varying normal pressure were thoroughly investigated. Three wear mechanisms were identified: abrasion in the running-in period, oxidn. during steady wear at low load levels, and adhesion at high loads. A higher particle vol. fraction raised the transition load but increased the wear rate in the abrasion and adhesion regimes. Increase of particle size was more effective than increase of vol. fraction to prolong the transition from mild wear to adhesive wear. The reasons for different wear mechanisms were detd. by analyses of the worn surfaces and wear debris.
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    Khatri, S.; Koczak, M. Formation of TiC in in situ processed composites via solid-gas, solid-liquid and liquid-gas reaction in molten Al-Ti. Mater. Sci. Eng.A 1993, 162, 153– 162,  DOI: 10.1016/0921-5093(90)90040-A
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    Das, S.; Prasad, S. V.; Ramachandran, T. R. Microstructure and wear of cast (Al-Si alloy)-graphite composites. Wear. 1989, 133, 173– 187,  DOI: 10.1016/0043-1648(89)90122-1
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    Microstructure and wear of cast (aluminum-silicon alloy)-graphite composites
    Das, S.; Prasad, S. V.; Ramachandran, T. R.
    Wear (1989), 133 (1), 173-87CODEN: WEARAH; ISSN:0043-1648.
    LM13 of near-eutectic and LM30 of hypereutectic compn. were chosen as matrix alloys. Composites and matrix alloys were heat treated to produce different morphols. of Si ranging from platelike in die-cast alloys to near spherical in heat-treated alloys. Wear tests were conducted under dry and partially lubricated conditions with SAE30 oil on a pin-on-disk wear test app. against a rotating steel EN25 counterbody. In partially lubricated wear tests, the sliding velocity was 1.4-4.6 m/s, and the applied pressure was 1.0-5.0 MPa. The pressure-velocity limits of all matrix alloys and composites with different microstructures were evaluated. Heat-treated composites possess superior wear rate, seizure resistance, and pressure-velocity limits as compared with those of die-cast composites and matrix alloys. Worn surfaces of heat-treated composites showed a graphite film, while those of die-cast alloys and composites showed surface fracture. The role of graphite particle dispersion and morphol. of Si on the sliding wear is discussed.
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    Ramesh, C. S.; Keshavamurthy, R.; Channabasappa, B. H.; Pramod, S. Friction and wear behavior of Ni–P coated Si3N4 reinforced Al6061 composites. Tribol. Int. 2010, 43, 623– 634,  DOI: 10.1016/j.triboint.2009.09.011
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    Friction and wear behavior of Ni-P coated Si3N4 reinforced Al6061 composites
    Ramesh, C. S.; Keshavamurthy, R.; Channabasappa, B. H.; Pramod, S.
    Tribology International (2010), 43 (3), 623-634CODEN: TRBIBK; ISSN:0301-679X. (Elsevier Ltd.)
    Al6061 matrix composite reinforced with nickel coated silicon nitride particles were manufd. by liq. metallurgy route. Microstructure and tribol. properties of both matrix alloy and developed composites have been evaluated. Dry sliding friction and wear tests were carried out using pin on disk type machine over a load range of 20-100 N and sliding velocities of range 0.31-1.57 m/s. Results revealed that, nickel coated silicon nitride particles are uniformly distributed through out the matrix alloy. Al6061-Ni-P-Si3N4 composite exhibited lower coeff. of friction and wear rate compared to matrix alloy. The coeff. of friction of both matrix alloy and developed composite decreased with increase in load up to 80 N. Beyond this, with further increase in the load, the coeff. of friction increased slightly. However, with increase in sliding velocity coeff. of friction of both matrix alloy and developed composite increases continuously. Wear rates of both matrix alloy and developed composites increased with increase in both load and sliding velocity. Worn surfaces and wear debris was examd. using SEM for possible wear mechanisms. Energy dispersive spectroscope (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) techniques were used to identify the oxides formed on the worn surfaces and wear debris.
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    Tung, S. C.; McMillan, M. L. Automotive tribology overview of current advances and challenges for the future. Tribol. Int. 2004, 37, 517– 536,  DOI: 10.1016/j.triboint.2004.01.013
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    Automotive tribology overview of current advances and challenges for the future
    Tung, Simon C.; McMillan, Michael L.
    Tribology International (2004), 37 (7), 517-536CODEN: TRBIBK; ISSN:0301-679X. (Elsevier Ltd.)
    A review. This keynote address will provide a comprehensive overview of various lubrication aspects of a typical powertrain system including the engine, transmission, driveline, and other components, as well as the integration of these lubrication and surface engineering concepts into a unified automotive powertrain system. In addn., this presentation will focus on the current status and future trends in automotive lubricants including discussion of current and anticipated future requirements of automotive engine oils. This presentation will also review the current std. ASTM (American Society for Testing and Materials) test methods for engine lubricants and other compilations of automotive stds. In addn. to engine oil test development, industrial researchers are developing light-wt. materials such as non-ferrous materials (Al, Mg) for engine and drivetrain materials to replace the current heavy-wt. cast iron blocks. Recent industrial developments include high strength and high d. of composite materials, high vol. liq. molding and hydroforming technol., structural adhesive boding, and the ability to mold large structural components. Industrial researchers have also developed processing improvements for forming more complex stamped aluminum parts or panels, more robust stamping, and improved casting techniques. In this paper, our insights and perspectives on future trends in light-wt. tribol. material and nonotribol. will also be reviewed.
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    Ceschini, L.; Minak, G.; Morri, A. Tensile and fatigue properties of the AA6061/20 vol% Al2O3p and AA7005/10 vol% Al2O3p composites. Compos. Sci. Technol. 2006, 66, 333– 342,  DOI: 10.1016/j.compscitech.2005.04.044
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    Tensile and fatigue properties of the AA6061/20vol.% Al2O3p and AA7005/10vol.% Al2O3p composites
    Ceschini, L.; Minak, G.; Morri, A.
    Composites Science and Technology (2006), 66 (2), 333-342CODEN: CSTCEH; ISSN:0266-3538. (Elsevier B.V.)
    In this paper, the tensile properties and the low-cycle fatigue behavior of the 7005 aluminum alloy reinforced with 10 vol% of Al2O3 particles (W7A10A composite) and 6061 aluminum alloy reinforced with 20 vol% of Al2O3 particles (W6A20A composite) were studied. The microstructural analyses showed clustering of Al2O3 particles, irregularly shaped and with a non-uniform size. A significant increase of the elastic modulus and tensile strength in the MMCs, respect to the unreinforced alloys, was evidenced by the tensile tests, while the elongation to fracture decreased. The temp. effect on the tensile properties was not relevant up to 150°C, while strength significantly decreased at 250°C, mainly in the composite with the lower content of the ceramic reinforcement. The low-cycle fatigue tests showed no evidence of isotropic hardening or softening for the W7A10A, and a slight cyclic softening for the W6A20A. SEM analyses of the fracture surfaces showed that both the tensile and fatigue fracture was controlled by interfacial decohesion (expecially for the W7A10A composite), fracture of reinforcing particles (mainly for the W6A20A composite), void nucleation and growth. Also the presence of the MgAl2O4 spinel, probably, played a significant role in the mechanisms of failure in the W6A20A composite, by promoting void nucleation at the particles-matrix interfaces, interfacial decohesion, and also failure of the particles. These effects can be responsible of the slight softening obsd. in the W6A20A, under the low-cycle fatigue conditions.
  20. 20
    Doel, T. J. A.; Bowen, P. Tensile properties of particulate-reinforced metal matrix composites. Composites, Part A 1996, 27, 655– 665,  DOI: 10.1016/1359-835X(96)00040-1
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    Tensile properties of particulate-reinforced metal matrix composites
    Doel, T. J. A.; Bowen, P.
    Composites, Part A: Applied Science and Manufacturing (1996), 27A (8), 655-665CODEN: CASMFJ; ISSN:1359-835X. (Elsevier)
    Room temp. tensile tests have been carried out on MMCs, all based on the Al alloy 7075 and on monolithic material. The particulate reinforcements used were SiC in three nominal sizes, 5, 13 and 60 μm. Three matrix aging conditions were studied, peak aged and equiv. underaged and overaged matrix conditions, based on microhardness measurements. The effects of aging condition on the tensile properties of the composites follow those produced in unreinforced material. Composites contg. 5 and 13 μm particles both had greater 0.2% proof stress and tensile strength values than unreinforced material. However, the composite reinforced with 60 μm particles had reduced 0.2% proof stress and tensile strength in the underaged and peak aged condition, and a greater 0.2% proof stress in the overaged condition compared to the monolithic alloy. All the composites had lower ductility than the unreinforced material, with the material contg. 5 μm SiC being the most ductile and that reinforced with 60 μm SiC having very low ductility. Failure appears to occur by the accumulation of internal damage to particles either by particle fracture or interfacial failure. Such damage introduces voids which grow and lead to reduced ductility in these composites. Large 60 μm particles fracture easily at low applied stresses, leading to reduced 0.2% proof stress and premature failure compared to the other composites. The small 5 and 13 μm particles damage less easily and so these composites are stronger than the monolithic material and are more ductile than the composite reinforced with 50 μm particles.
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    Hong, S. J.; Kim, H. M.; Huh, D.; Suryanarayana, C.; Chun, B. S. Effect of clustering on the mechanical properties of SiC particulate-reinforced aluminum alloy 2024 metal matrix composites. Mater. Sci. Eng., A 2003, 347, 198– 204,  DOI: 10.1016/S0921-5093(02)00593-2
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    Effect of clustering on the mechanical properties of SiC particulate-reinforced aluminum alloy 2024 metal matrix composites
    Hong, Soon-Jik; Kim, Hong-Moule; Huh, Dae; Suryanarayana, C.; Chun, Byong Sun
    Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing (2003), A347 (1-2), 198-204CODEN: MSAPE3; ISSN:0921-5093. (Elsevier Science B.V.)
    Al 2024/SiC metal matrix composite powders produced by centrifugal atomization were hot extruded to investigate the effect of clustering on their mech. properties. Fracture toughness and tensile tests were conducted on specimens reinforced with 3-10 vol.% SiC. A model was proposed to suggest that the strength of the composite can be estd. from the load transfer model approach that takes into consideration the extent of clustering. This model has been successful in predicting the exptl. obsd. strength and fracture toughness values of the Al 2024-SiC composites. On the basis of exptl. observations, the strength of particulate-reinforced composites may be calcd. from the relation σy = σmVm + σr(Vr-Vc) - σrVc, where σ and V represent the yield strength and vol. fraction, resp., and the subscripts m, r, and c represent the matrix, reinforcement, and clusters, resp.
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    Al-Qutub, A. M.; Allam, I. M.; Qureshi, T. W. Wear properties of 10% sub-micron Al2O3/6061 aluminium alloy composite. Int. J. Appl. Mech. Eng. Mech. 2002, 7, 329– 334
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    Wear properties of 10% sub-micron AL2O3/6061 aluminum alloy composite
    Al-Qutub, A. M.; Allam, I. M.; Qureshi, T. W.
    International Journal of Applied Mechanics and Engineering (2002), 7 (Spec. Issue), 329-334CODEN: IJAMAJ ISSN:. (University of Zielona Gora)
    The effect of reinforcing 6061 Aluminum alloy with 10% sub-micron Al2O3 by vol. on the wear properties was studied using a pin-on-disk type tribometer as well as Vickers micro-Hardness tester. The dry wear test, for the alloy and the composite, was performed at room temp. under different loads with a relative speed of 1 m/s. The pin was either made of the 6061 alloy or the composite. The counter face was made of AISI 4140 tool steel disk. Three wear mechanisms were obsd.: abrasion, surface fatigue, and adhesion. Almost all wear mechanisms were obsd. in combination under different loads. However, abrasion was dominant at low loads, delamination wear was dominant at higher loads and adhesion was more clear at extreme loads. The presence of sub-micron Al2O3 particles in the composite increased both hardness and wear resistance. Depending on the load, the wear resistance increased by 20% to 106% with the ceramic reinforcement. Also, the transition load, from mild to sever wear, was increased due to the addn. of the ceramic.
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    Kouzeli, M.; Dunand, D. C. Effect of reinforcement connectivity on the elasto-plastic behavior of aluminum composites containing sub-micron alumina particles. Acta Mater. 2003, 51, 6105– 6121,  DOI: 10.1016/S1359-6454(03)00431-2
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    Effect of reinforcement connectivity on the elasto-plastic behavior of aluminum composites containing sub-micron alumina particles
    Kouzeli, M.; Dunand, D. C.
    Acta Materialia (2003), 51 (20), 6105-6121CODEN: ACMAFD; ISSN:1359-6454. (Elsevier Ltd.)
    The mech. properties of composites consisting of an aluminum matrix with 34 and 37 vol.% sub-micron Al2O3 particles were studied in compression for two reinforcement architectures: interconnected and discontinuous. Both the elastic and plastic behaviors of these composites are successfully modeled using a self-consistent approach: the classical self-consistent and the three-phase self-consistent models for the interconnected and discontinuous architectures, resp. At ambient temp., an interconnected architecture offers only a modest increase in stiffness and strength over a discontinuous architecture of equal vol. fraction. At elevated temps. (250, 500 and 600 °C), the interconnected reinforcement becomes increasingly more effective at strengthening the composites. However, the relative increase in strength due to interconnectivity can only be exploited at small strains (1-5%) due to the early development of compressive flow instabilities in the interconnected composites. While microstructural damage controls the instability strain of the interconnected composites at ambient temp., their low strain-hardening coeff. is the main contribution to flow instabilities at elevated temp.
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    Wang, X.; Wu, G.; Sun, D.; Qin, C.; Tian, Y. Micro-yield property of sub-micron Al2O3 particle reinforced 2024 aluminum matrix composite. Mater. Lett. 2004, 58, 333– 336,  DOI: 10.1016/S0167-577X(03)00481-6
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    Ray, S. Synthesis of cast metal matrix particulate composites. J. Mater. Sci. 1993, 28, 5397– 5413,  DOI: 10.1007/BF00367809
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    Synthesis of cast metal matrix particulate composites
    Ray, S.
    Journal of Materials Science (1993), 28 (20), 5397-413CODEN: JMTSAS; ISSN:0022-2461.
    The present review with 67 refs. begins by briefly tracing history in the early days of development of cast metal-matrix composites and also outlines different casting routes for their synthesis. The problems faced by the quality of cast products and their relation to the process variables and characteristics of a given process, constitute the main theme of the review. The development of microstructure was discussed in view of nucleation behavior anticipated on the basis of estd. interface energies. The solidification around dispersoids and in regions away from it was highlighted. Porosity in cast composites (its origin and control in cast components by suitable mold design) has engaged attention because of damage to mech. properties due to porosity. The chem. reactions at the interface between dispersoid and matrix during processing of certain important systems of composites, were described and the means of controlling these reactions were indicated. The review concludes by drawing attention to the potential for application of cast composites in different industrial components and underlines the necessity of research in certain related fields so that industrial application of cast metal-matrix composites will soon become a reality.
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    Prabhavalkar, Y.; Chapgaon, A. N. Effect of volume fraction of Al2O3 on tensile strength of aluminium 6061 by varying stir casting furnace parameters: A review. Int. Res. J. Eng. Technol. 2017, 4, 1351– 1355
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    Mazahery, A.; Shabani, M. O. Microstructural and abrasive wear properties of SiC reinforced aluminum-based composite produced by compocasting. Trans. Nonferrous Met. Soc. China 2013, 23, 1905– 1914,  DOI: 10.1016/S1003-6326(13)62676-X
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    Microstructural and abrasive wear properties of SiC reinforced aluminum-based composite produced by compocasting
    Mazahery, Ali; Shabani, Mohsen Ostad
    Transactions of Nonferrous Metals Society of China (2013), 23 (7), 1905-1914CODEN: TNMCEW; ISSN:1003-6326. (Elsevier B.V.)
    The effect of SiC particles reinforcement with av. size of 1, 5, 20 and 50 μm and vol. fraction of 5%, 10% and 15% on the microstructure and tribol. properties of Al-based composite was investigated. Composites were produced by applying compocasting process. Tribol. properties of the unreinforced alloy and composites were studied using pin-on-disk wear tester, under dry sliding conditions at different specific loads. The influence of secondary mech. processing with different rolling redns. on the dry sliding wear characteristics of Al matrix composites was also assessed. Hardness measurement and SEM were used for microstructural characterization and investigation of worn surfaces and wear debris. The proper selection of process parameter such as pouring temp., stirring speed, stirring time, pre-heated temp. of reinforcement can all influence the quality of the fabricated composites. The porosity level of composite should be minimized and the chem. reaction between the reinforcement and matrix should be avoided.
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    Bharath, V.; Ajawan, S. S.; Nagaral, M.; Auradi, V.; Kori, S. A. Characterization and Mechanical Properties of 2014 Aluminum Alloy Reinforced with Al 2 O 3p Composite Produced by Two-Stage Stir Casting Route. J. Inst. Eng. (India): Ser. C 2019, 100, 277– 282,  DOI: 10.1007/s40032-018-0442-x
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    Auradi, V.; Rajesh, G. L.; Kori, S. A. Processing of B4C Particulate Reinforced 6061Aluminum Matrix Composites by melt stirring involving two-step addition. Procedia Mater. Sci. 2014, 6, 1068– 1076,  DOI: 10.1016/j.mspro.2014.07.177
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    Processing of B4C Particulate Reinforced 6061Aluminum Matrix Composites by Melt Stirring Involving Two-step Addition
    Auradi, V.; Rajesh, G. L.; Kori, S. A.
    Procedia Materials Science (2014), 6 (), 1068-1076CODEN: PMSREM; ISSN:2211-8128. (Elsevier B.V.)
    In the present work, 11wt% B4C particulate reinforced 6061 Al matrix composites were produced by conventional melt stirring method. Processing of composite is carried out at a temp. of 750 °C involving two stage addns. Preheated B4C particles along with K2TiF6 halide salt (with ratio of 0.3) was introduced in steps of two rather than adding all at once. Characterization of the prepd. composites is done using SEM/EDX and X-RD studies. Fairly uniform distribution of B4C particulates without clustering in 6061Al matrix was evident from SEM studies. The prepd. composite consists of α-Al, B4C and minor phases like Al3Ti, AlB2 and Al3BC are confirmed by XRD studies. The addn. of B4C particulates to 6061Al matrix has resulted in improvements in mech. properties of the base alloy.
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    Sajjadi, S. A.; Ezatpour, H. R.; Parizi, M. T. Comparison of microstructure and mechanical properties of A356 aluminum alloy/Al2O3 composites fabricated by stir and compo-casting processes. Mater. Des. 2012, 34, 106– 111,  DOI: 10.1016/j.matdes.2011.07.037
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    Comparison of microstructure and mechanical properties of A356 aluminum alloy/Al2O3 composites fabricated by stir and compo-casting processes
    Sajjadi, S. A.; Ezatpour, H. R.; Torabi Parizi, M.
    Materials & Design (2012), 34 (), 106-111CODEN: MADSD2; ISSN:0264-1275. (Elsevier Ltd.)
    Metal-matrix composites (MMCs), as light and strong materials, are very attractive for application in different industries. In the present work, nano and micro-composites (A356/Al2O3) with different wt. percent of particles were fabricated by two melt techniques such as stir-casting and compo-casting. Microstructural characterization was investigated by optical (OP) and SEM. Tensile, hardness and compression tests were carried out in order to identify mech. properties of the composites. The results of microstructural study revealed uniform distribution, grain refinement and low porosity in micro and nano-composite specimens. The mech. results showed that the addn. of alumina (micro and nano) led to the improvement in yield strength, ultimate tensile strength, compression strength and hardness. It was indicated that type of fabrication process and particle size were the effective factors influencing on the mech. properties. Decreasing alumina particle size and using compo-casting process obtained the best mech. properties.
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    Zulfia, A.; Putro, E. C.; Wahyudi, M.; Dhaneswara, D.; Utomo, B. W. Fabrication and characteristics of ADC-12 reinforced nano-SiC and nano-Al2O3 composites through stir casting route. IOP Conf. Ser.: Mater. Sci. Eng. 2018, 432, 012032,  DOI: 10.1088/1757-899X/432/1/012032
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    Fabrication and characteristics of ADC-12 reinforced nano-SiC and nano-Al2O3 composites through stir casting route
    Zulfia, A.; Putro, E. C.; Wahyudi, M.; Dhaneswara, D.; Utomo, B. W.
    IOP Conference Series: Materials Science and Engineering (2018), 432 (1st Materials Research Society Indonesia Conference and Congress, 2017), 012032/1-012032/8CODEN: ICSMGW; ISSN:1757-899X. (IOP Publishing Ltd.)
    Aluminum ADC-12 reinforced with nano-SiC and nano-Al2O3 have been successfully produced by stir casting method. The effect of addn. nano SiC and Al2O3 into matrix has been studied with variation of 0.05, 0.10, 0.15, 0.20, 0.30 vf-% for each composites. The addn. of Mg was introduced with 10 wt-% to promote wetting between molten Al and ceramic particle reinforcement. The OES result shows decreasing amt. of excess Si and Mg in the composite compared to as-cast ADC-12. One of the main intermetallic phases present evenly in aluminum matrix is Mg2Si which was confirmed by EDS and XRD. The highest tensile strength and hardness of composites were achieved by the addn. of 0.15 and 0.30%vf SiC and Al2O3, resp., with the values of 111 and 115 MPa and 42 and 41 HRB. The increasing hardness generated significant improvement in wear resistance of composites. The higher the reinforcement content, the higher the porosity formed, due to the tendency of dewetting as well as nano particles agglomeration.
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    Kumar, B. P.; Birru, A. K. Microstructure and mechanical properties of aluminium metal matrix composites with addition of bamboo leaf ash by stir casting method. Trans. C. Soc. China 2017, 27, 2555– 2572,  DOI: 10.1016/S1003-6326(17)60284-X
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    Liu, X.; Zhang, P.; He, S.; Xu, Q.; Dou, Z.; Wang, H. Effect of beryllium content and heat treatment on microstructure and yield strength in Be/6061Al composites. J. Alloys Compd. 2018, 743, 746– 755,  DOI: 10.1016/j.jallcom.2018.02.060
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    Effect of beryllium content and heat treatment on microstructure and yield strength in Be/6061Al composites
    Liu, Xiangdong; Zhang, Pengcheng; He, Shixiong; Xu, Qingdong; Dou, Zuoyong; Wang, Haijun
    Journal of Alloys and Compounds (2018), 743 (), 746-755CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)
    6061Al alloy was selected as the matrix of beryllium-aluminum composites and Be/6061Al composites with 20wt% Be, 40 wt% Be and 62 wt%Be were prepd. by hot isostatic pressing sintering technol. The microstructure and interface characteristics of Be/6061Al composites were investigated and characterized by SEM and TEM. The results showed that Be/6061Al composites were made up of Be phase and Al rich phase and there was no reaction product at the interface. Be phase and Al-rich phase combined mech. and kept a certain orientation relationship in Be/6061Al composite. The yield strength of Be/6061Al composites increased with the increase of Be content, which could be predicted by modified shear lag model. Mg and Si formed β'' and pptd. in the Al matrix after artificially aging treatment and dramatically improved the yield strength of Be/6061Al composites.
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    Mohanavel, V.; Rajan, K.; Kumar, S. S.; Vijayan, G.; Vijayanand, M. S. Study on mechanical properties of graphite particulates reinforced aluminium matrix composite fabricated by stir casting technique. Mater. Today: Proc. 2018, 5, 2945– 2950,  DOI: 10.1016/j.matpr.2018.01.090
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    Study on mechanical properties of graphite particulates reinforced aluminum matrix composite fabricated by stir casting technique
    Mohanavel, V.; Rajan, K.; Suresh Kumar, S.; Vijayan, G.; Vijayanand, M. S.
    Materials Today: Proceedings (2018), 5 (1_Part_3), 2945-2950CODEN: MTPAC4; ISSN:2214-7853. (Elsevier Ltd.)
    The lineage of applied materials science is always in demand for light wt. and highly performing materials. Such materials would find their applications in aircraft, structural, non-structural and automobile industries, etc. The present research study focuses on the prodn. of aluminum (AA6351) matrix composites reinforced in different mass fractions of graphite particulates by using stir casting method. The mass fraction of reinforcement was varied from 0% to 12% in stages of 4%. Hardness and tensile strength of the composite were investigated. The microstructures of the produced composites were examd. by scanning electron microg. test. The SEM images revealed the non-homogeneous distribution of graphite (Gr) particles in the matrix and this may be due to low d. of graphite. The test results revealed that the mech. properties of the composite decrease with increase in the mass fraction of graphite particle content, this may be due to poor interfacial bonding between the reinforcement and the matrix. The brittle nature of the reinforcing particles (graphite) plays a vital role in decreasing the mech. properties because the graphite as a soft reinforcement is brittle in nature and so it enhanced the brittleness in the AMCs.
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    Sharma, V. K.; Singh, R. C.; Chaudhary, R. Effect of flyash particles with aluminium melt on the wear of aluminium metal matrix composites. JESTECH. 2017, 20, 1318– 1323,  DOI: 10.1016/j.jestch.2017.08.004
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    Sekar, K.; Kanjirathikal, A.; Joseph, M. A. Effect of T6 Heat Treatment in Tribological Properties of A356 Aluminum Alloy Reinforced with Al2O3 Nanoparticles by Combination Effect of Stir and Squeeze Casting Method. Appl. Mech. Mater. 2014, 592, 968– 971,  DOI: 10.4028/www.scientific.net/AMM.592-594.968
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    Effect of T6 heat treatment in tribological properties of A356 aluminum alloy reinforced with Al2O3 nano particles by combination effect of stir and squeeze casting method
    Sekar, K.; Allesu, K.; Joseph, M. A.
    Applied Mechanics and Materials (2014), 592-594 (Dynamics of Machines and Mechanisms, Industrial Research), 968-971CODEN: AMMPDO; ISSN:1662-7482. (Trans Tech Publications Ltd.)
    A356 alloys are attractive alternative for automotive and aeronautical applications. In this work the effects of T6 heat treatment in tribol. properties of A356 alloy reinforced with Al2O3 nano particles of size 30nm are investigated. The percentage inclusions Al2O3 were varied from 0.5 to 1.5wt%. The particles were added with stirring at 400rpm and squeeze casting at 750°C and pressure of 600MPa in the squeeze casting machine. The tribol. properties of the samples were also investigated by pin-on-disk tests at 10,30,50and 70N, sliding speed 0.534m/s and sliding distance 1100m in dry condition. The lowest dry wear rate obtained through T6 heat treatment condition.
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    Kok, M. Production and mechanical properties of Al2O3 particle-reinforced 2024 aluminium alloy composites. J. Mater. Process. Technol. 2005, 161, 381– 387,  DOI: 10.1016/j.jmatprotec.2004.07.068
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    Production and mechanical properties of Al2O3 particle-reinforced 2024 aluminium alloy composites
    Kok, M.
    Journal of Materials Processing Technology (2005), 161 (3), 381-387CODEN: JMPTEF; ISSN:0924-0136. (Elsevier B.V.)
    2024 Aluminum alloy metal matrix composites (MMCs) reinforced with three different sizes and wt. fractions of Al2O3 particles up to 30 wt.% were fabricated by a vortex method and subsequent applied pressure. The effects of Al2O3 particle content and size of particle on the mech. properties of the composites such as hardness and tensile strength were investigated. The d. measurements showed that the samples contained little porosity, and the amt. of porosity in the composites increased with increasing wt. fraction and decreasing size of particles. Scanning electron microscopic observations of the microstructures revealed that the dispersion of the coarser sizes of particles was more uniform while finer particles led to agglomeration of the particles and porosity. The results show that the hardness and the tensile strength of the composites increased with decreasing size and increasing wt. fraction of particles.
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    The microstructure and hardness of Al2O3 particle reinforced composite
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    Aluminum alloys (Al2014 and Al2124 alloy) and their composites contg. 10wt.% Al2O3 with 3 μm and 43 μm sizes of particles have been produced by powder metallurgy (PM) method and the microstructure and hardness were investigated. SEM investigation showed a nearly uniform distribution of the Al2O3 particles within the Al2124 alloy matrix although some porosities were found in the Al2014 alloy matrix. Furthermore, it was found that the macrohardness of Al2124 alloy composite improved highly in comparison to that of Al2014 alloy due to fine of microstructure and increased hardness. The hardnesses of both MMCs increased with increasing the particle sizes.
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    Umanath, K.; Selvamani, S. T.; Palanikumar, K.; Raphael, T.; Prashanth, K. Effect of sliding distance on dry sliding wear behaviour of Al6061/SiC/Al2O3 hybrid composite. Proc. Int. Conf. Advances Mechanical Engineering 2013, 749– 756
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    Tian, K.; Zhao, Y.; Jiao, L.; Zhang, S.; Zhang, Z.; Wu, X. Effects of in situ generated ZrB2 nano-particles on microstructure and tensile properties of 2024Al matrix composites. J. Alloys Compd. 2014, 594, 1– 6,  DOI: 10.1016/j.jallcom.2014.01.117
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    Effects of in situ generated ZrB2 nano-particles on microstructure and tensile properties of 2024Al matrix composites
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    Journal of Alloys and Compounds (2014), 594 (), 1-6CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)
    The main purpose of this paper is to investigate the effects of nano-size ZrB2 particles on the microstructure and tensile properties of 2024Al matrix composites. The microstructure and tensile properties of the 2024Al matrix composites reinforced by ZrB2 nano-particles fabricated from 2024Al-K2ZrF6-KBF4 system by direct melt reaction are investigated by XRD, OM, SEM, EDS, TEM and tensile testing. The results reveal that the ZrB2 nano-particles exhibit rectangular and nearly hexagon shape with the size ranging from 30 to 100 nm, and the reasonable uniform distribution of ZrB2 nano-particles gives rise to significant grain refinement of 2024Al alloy. Tensile testing results show that the tensile strength and yield stress of the composites increase continuously. However, the elongation of the composites increases almost linearly and declines later as the increasing of ZrB2 content. The fracture morphologies are in accord with corresponding ductility results. What's more, the strengthening mechanism of ZrB2 nano-particles is established.
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    Harti, J. I.; Prasad, T. B.; Nagaral, M.; Jadhav, P.; Auradi, V. Microstructure and dry sliding wear behaviour of Al2219-TiC composites. Mater. Today: Proc. 2017, 4, 11004– 11009,  DOI: 10.1016/j.matpr.2017.08.058
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    Li, M.; Ma, K.; Jiang, L.; Yang, H.; Lavernia, E. J.; Zhang, L.; Schoenung, J. M. Synthesis and mechanical behavior of nanostructured Al 5083/n-TiB2 metal matrix composites. Mater. Sci. Eng.A 2016, 656, 241– 248,  DOI: 10.1016/j.msea.2016.01.031
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    Synthesis and mechanical behavior of nanostructured Al 5083/n-TiB2 metal matrix composites
    Li, Meijuan; Ma, Kaka; Jiang, Lin; Yang, Hanry; Lavernia, Enrique J.; Zhang, Lianmeng; Schoenung, Julie M.
    Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing (2016), 656 (), 241-248CODEN: MSAPE3; ISSN:0921-5093. (Elsevier B.V.)
    Nanostructured Al 5083-based composites with nano-TiB2 reinforcement particles were fabricated via cryomilling and spark plasma sintering (SPS). TEM observation revealed that the Al matrix consists of equiaxed nano-grains (av. size, ∼74 nm), and the reinforcement, TiB2 nanoparticles (n-TiB2), was distributed discretely and homogeneously in the Al matrix. The interface between the Al-matrix and n-TiB2 appears to be free of defects, and no obvious discontinuities were obsd. The composite exhibits a compressive strength of 817 MPa with 6.0% strain-to-failure. The strength is 20% higher than that of an equiv. SPS consolidated Al 5083 without reinforcement. Nanoindentation was used in our study to provide fundamental insight into the local microscopic mech. properties. The strengthening mechanisms of the composites are analyzed taking into account the grain boundaries, the Orowan strengthening from the n-TiB2 particles and dispersoids such as Al2O3, AlN and Al6Mn, as well as geometrically necessary dislocations induced in the matrix by the nano-TiB2 particles.
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    Investigation of tribological and mechanical properties Al2O3-SiC reinforced Al composites manufactured by casting or P/M method
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    Materials & Design (2008), 29 (10), 2002-2008CODEN: MADSD2; ISSN:0264-1275. (Elsevier Ltd.)
    In this study, Al based Al2O3 and SiC particle reinforced composite materials were manufd. by casting or P/M method. Tribol. properties of these composite materials were investigated by wearing with 10 N load and 50 rpm on a pin-on-disk wear test rig at dry conditions. Mech. properties were investigated. The effects of reinforce materials on tribol. and mech. properties were investigated. In addn. to that microstructure of these materials were investigated by optical and SEM microscope. Tribol. and hardness properties of composites significantly improved by the use of particle reinforced into Al.
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    Ramachandra, M.; Abhishek, A.; Siddeshwar, P.; Bharathi, V. Hardness and wear resistance of ZrO2 nano particle reinforced Al nanocomposites produced by powder metallurgy. Procedia Mater. Sci. 2015, 10, 212– 219,  DOI: 10.1016/j.mspro.2015.06.043
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    Hardness and Wear Resistance of ZrO2 Nano Particle Reinforced Al Nanocomposites Produced by Powder Metallurgy
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    Procedia Materials Science (2015), 10 (), 212-219CODEN: PMSREM; ISSN:2211-8128. (Elsevier B.V.)
    Nano particle reinforced Aluminum Nanocomposites are produced using Zirconium dioxide (n-ZrO2). Nano particles produced by soln. combustion method. Urea is used as fuel and then reinforcing into Aluminum matrix in different percentages by wt. using the powder metallurgy technique. The specimens prepd. are tested for their hardness and microstructure. The above mentioned properties were chosen due to the reinforcement added (n-ZrO2) which is known to have good toughness and hardness among other structural properties at room temp. The composites are tested for wear resistance by using pin on disk wear testing machine. Study of Wear mechanisms, Microstructure were performed on sintered specimens. Microstructure revealed near uniform distribution of n-ZrO2 particles with slight agglomeration. The microstructure also revealed good interfacial bond between matrix and n-ZrO2 particles. Incorporation of n-ZrO2 particles in aluminum matrix can lead to the prodn. of aluminum composites with improved hardness and wear resistance. These composites can find applications in automotive components like pistons, cylinder liners and connecting rods.
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    Prabu, S. B.; Karunamoorthy, L.; Kathiresan, S.; Mohan, B. Influence of stirring speed and stirring time on distribution of particles in cast metal matrix composite. J. Mater. Process. Technol. 2006, 171, 268– 273,  DOI: 10.1016/j.jmatprotec.2005.06.071
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    Influence of stirring speed and stirring time on distribution of particles in cast metal matrix composite
    Prabu, S. Balasivanandha; Karunamoorthy, L.; Kathiresan, S.; Mohan, B.
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    In the present study, high silicon content aluminum alloy-silicon carbide metal matrix composite material, with 10%SiC were successfully synthesized, using different stirring speeds and stirring times. The microstructure of the produced composites was examd. by optical microscope and scanning electron microscope. The Brinell hardness test was performed on the composite specimens from base of the cast to top. The results revealed that stirring speed and stirring time influenced the microstructure and the hardness of composite. Microstructure anal. revealed that at lower stirring speed with lower stirring time, the particle clustering was more. Increase in stirring speed and stirring time resulted in better distribution of particles. The hardness test results also revealed that stirring speed and stirring time have their effect on the hardness of the composite. The uniform hardness values were achieved at 600 rpm with 10 min stirring. But beyond certain stir speed the properties degraded again. An attempt is made in this study to establish the trend between processing parameters such as stirring speed and stirring time with microstructure and hardness of composite.
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    Singla, M.; Dwivedi, D. D.; Singh, L.; Chawla, V. Development of aluminium based silicon carbide particulate metal matrix composite. J. Miner. Mater. Charact. Eng. 2009, 8, 455– 467,  DOI: 10.4236/jmmce.2009.86040
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    Abrasive wear of zircon sand and alumina reinforced Al-4.5wt%Cu alloy matrix composites - A comparative study
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    Composites Science and Technology (2007), 67 (3-4), 746-751CODEN: CSTCEH; ISSN:0266-3538. (Elsevier B.V.)
    In the present investigation a comparative study on abrasive wear behavior of aluminum metal matrix composite reinforced with alumina and zircon sand particles has been carried out. Microstructures of the composites in as-cast condition show uniform distribution of particles and reveal better bonding in the case of zircon particles reinforced composite compared to that in alumina particles reinforced composite. Abrasive wear resistance of both the composites improves with the decrease in particle size. It is obsd. that the alumina particle reinforced composite shows relatively poor wear resistance property compared to zircon-reinforced composite.
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    Youssef, Y. M.; Dashwood, R. J.; Lee, P. D. Effect of clustering on particle pushing and solidification behaviour in TiB2 reinforced aluminium PMMCs. Composites, Part A 2005, 36, 747– 763,  DOI: 10.1016/j.compositesa.2004.10.027
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    Effect of clustering on particle pushing and solidification behaviour in TiB2 reinforced aluminium PMMCs
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    Composites, Part A: Applied Science and Manufacturing (2005), 36A (6), 747-763CODEN: CASMFJ; ISSN:1359-835X. (Elsevier)
    The behavior of titanium diboride particles in molten aluminum was investigated by conducting casting expts. at different cooling rates and particle addn. levels, starting with a master alloy contg. in situ formed TiB2 particles. The particle pushing/engulfment phenomena and particle clustering effects were studied for two matrix alloy systems, com. purity (CP) aluminum and an Al-4% Mg (A514) alloy. The crit. velocity, which is the solidification velocity below which the particles are pushed and above which they are engulfed, was calcd. The results were validated against the predictions of the models available in the literature. The assumptions, limitations and comparative success of the different models were discussed. The crit. velocity obsd. in CP-Al ranged between 4 and 8 μm/s at low particulate concn. (<1 vol%) and decreased to less than 2 μm/s for the high concn. of particles. In the case of A514, the crit. velocity was lower at the low particulate concn. (between 2 and 3 μm/s). The hypothesis that particle clustering could result in erroneous crit. velocity predictions was explored and it was concluded that particle clustering must be included for accurate prediction of particle pushing in these alloys.
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    Nakae, H.; Wu, S. Engulfment of Al2O3 particles during solidification of aluminum matrix composites. Mater. Sci. Eng.A 1998, 252, 232– 238,  DOI: 10.1016/S0921-5093(98)00664-9
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    Engulfment of Al2O3 particles during solidification of aluminum matrix composites
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    Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing (1998), A252 (2), 232-238CODEN: MSAPE3; ISSN:0921-5093. (Elsevier Science S.A.)
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    Dry sliding wear maps for AA7010 (Al-Zn-Mg-Cu) aluminium matrix composite
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    Tribology International (2013), 60 (), 77-82CODEN: TRBIBK; ISSN:0301-679X. (Elsevier Ltd.)
    Wear mechanism map for aluminum matrix composite helps in predicting and understanding different wear mechanisms in a material. It also identifies the crit. load and sliding speed for transition of one wear mechanism to other. In the present investigation, the wear coeff. is in the range of 10-4-10-5 which is at the boundary region between mild to severe wear. It is also obsd. from that there are four wear regimes; they are ultra mild wear, mild wear or oxidative wear, delamination wear and severe wear. All these facts are discussed on the basis of prevailing wear mechanism.
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    Cruz, K. S.; Meza, E. S.; Fernandes, F. A.; Quaresma, J. M.; Casteletti, L. C.; Garcia, A. Dendritic arm spacing affecting mechanical properties and wear behavior of Al-Sn and Al-Si alloys directionally solidified under unsteady-state conditions. Metall. Mater. Trans. A 2010, 41, 972– 984,  DOI: 10.1007/s11661-009-0161-2
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    Dendritic Arm Spacing Affecting Mechanical Properties and Wear Behavior of Al-Sn and Al-Si Alloys Directionally Solidified under Unsteady-State Conditions
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    Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science (2010), 41A (4), 972-984CODEN: MMTAEB; ISSN:1073-5623. (Springer)
    Alloys of Al-Sn and Al-Si are widely used in tribol. applications such as cylinder liners and journal bearings. Studies of the influence of the as-cast microstructures of these alloys on the final mech. properties and wear resistance can be very useful for planning solidification conditions in order to permit a desired level of final properties to be achieved. The aim of the present study was to contribute to a better understanding about the relationship between the scale of the dendritic network and the corresponding mech. properties and wear behavior. The Al-Sn (15 and 20 wt pct Sn) and Al-Si (3 and 5 wt pct Si) alloys were directionally solidified under unsteady-state heat flow conditions in water-cooled molds in order to permit samples with a wide range of dendritic spacings to be obtained. These samples were subjected to tensile and wear tests, and exptl. quant. expressions correlating the ultimate tensile strength (UTS), yield tensile strength, elongation, and wear vol. to the primary dendritic arm spacing (DAS) have been detd. The wear resistance was shown to be significantly affected by the scale of primary dendrite arm spacing. For Al-Si alloys, the refinement of the dendritic array improved the wear resistance, while for the Al-Sn alloys, an opposite effect was obsd., i.e., the increase in primary dendrite arm spacing improved the wear resistance. The effect of inverse segregation, which is obsd. for Al-Sn alloys, on the wear resistance is also discussed.
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    Murakami, T.; Kajino, S.; Nakano, S. High-temperature friction and wear properties of various sliding materials against aluminum alloy 5052. Tribol. Int. 2013, 60, 45– 52,  DOI: 10.1016/j.triboint.2012.10.015
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    High-temperature friction and wear properties of various sliding materials against aluminum alloy 5052
    Murakami, T.; Kajino, S.; Nakano, S.
    Tribology International (2013), 60 (), 45-52CODEN: TRBIBK; ISSN:0301-679X. (Elsevier Ltd.)
    The friction and wear properties of Si3N4-8mass% Al2O3-6mass% Y2O3, AISI H13 steel, AISI 52100 steel, Inconel 600, ZrO2-3 mol% Y2O3, WC-6mass% Co and BN-50mass% Ni disk specimens sliding against aluminum alloy 5052 were examd. at 823 K in air. The AISI H13 steel, AISI 52100 steel and BN-50mass% Ni disk specimens exhibited relatively stable friction coeffs. as low as 0.4-0.5, although the AISI 52100 steel and BN-50mass% Ni disk specimens exhibited the largest vol. increase and the highest specific wear rates, resp. On the other hand, the AISI H13 steel, ZrO2-3 mol% Y2O3 and WC-6mass% Co disk specimens exhibited much smaller vol. changes than AISI 52100 steel, Inconel 600 and BN-50mass% Ni disk specimens. However, the ZrO2-3 mol% Y2O3 and WC-6mass% Co disk specimens exhibited unstable friction coeffs. and the friction coeffs. as high as 0.6, resp. SEM-EDS analyses revealed large amt. of Al and oxygen on the worn surfaces of the Si3N4-8mass% Al2O3-6mass% Y2O3, AISI H13 steel, AISI 52100 steel and ZrO2-3 mol% Y2O3 disk specimens, while much smaller amt. of Al and oxygen were obsd. on the worn surfaces of the Inconel 600, WC-6mass% Co and BN-50mass% Ni disk specimens. In addn., distinct oxygen peaks were obsd. on the worn surfaces of all the aluminum alloy pin specimens, but such oxygen peaks were hardly obsd. on the non-worn surfaces of all the pin specimens.
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    Mittal, P.; Dixit, G. Dry sliding wear behaviour of 2014 aluminium alloy reinforced with SiC composite. Int. J. Eng. Res. Sci. Technol. 2016, 5, 147– 153,  DOI: 10.17577/IJERTV5IS060172
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    Contribution of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites
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    The relative contribution of three strengthening factors in particulate-reinforced metal matrix nanocomposites (MMNCs), namely, load-bearing effect, enhanced dislocation d. strengthening effect and Orowan strengthening effect, is evaluated. Orowan strengthening mechanism is found to play a significant role in MMNCs. The relative contribution of Orowan strengthening effect increases with decreasing size of nanoparticles. However, there exists a crit. particle size below which the Orowan strengthening effect drops abruptly. The crit. particle size, independent of the vol. fraction of nanoparticles, is found to be about 5.44 times the magnitude of the Burgers vector of dislocations in the matrix.
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    Zhang, Z.; Chen, D. L. Consideration of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites: A model for predicting their yield strength. Scr. Mater. 2006, 54, 1321– 1326,  DOI: 10.1016/j.scriptamat.2005.12.017
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    Consideration of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites: a model for predicting their yield strength
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    An anal. model for predicting the yield strength of particulate-reinforced metal matrix nanocomposites was developed. The strengthening effects involving (i) Orowan strengthening effect, (ii) enhanced dislocation d. due to the residual plastic strain caused by the difference in the coeffs. of thermal expansion between the matrix and particles and (iii) load-bearing effects were taken into account. The prediction is in good agreement with the exptl. data reported in the literature.
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    Thermal cycling behavior of extruded aluminum-silicon alloy (Al-7% Si-0.7% Mg) based composites reinforced with 10 and 20 vol% particulate silicon carbide and the matrix alloy was studied. The composites and the matrix alloy were thermally cycled between 100 and 430° with the applied stresses below the yield strength, ranging from 3 to 15 MPa. The elongation to fracture and m' values were detd. Under certain loading and thermal cycling conditions, composite samples exhibit fairly high ductility, >80%, with an increase in m' value. The evaluation of the microstructures and RA values show that the thermally cycled samples contain cavities of varying amt. along the gauge and exhibit higher homogeneous plastic deformation than those isothermally tensile tested at 430°.
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    Tjong, S. C.; Wang, G. S.; Mai, Y. W. Low-cycle fatigue behavior of Al-based composites containing in situ TiB2, Al2O3 and Al3Ti reinforcements. Mater. Sci. Eng.A 2003, 358, 99– 106,  DOI: 10.1016/S0921-5093(03)00266-1
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    Aluminum-based composites reinforced with in situ TiB2 and Al2O3 particles were prepd. through reactive hot pressing of TiO2, Al and B powders. Brittle Al3Ti blocks were also formed in situ when the B/TiO2 mol. ratio is smaller than 2. The low-cycle fatigue behavior of in situ composites under total strain-controlled conditions at room temp. was investigated. The results showed that the composite reinforced with in situ TiB2 and Al2O3 particles exhibits a relatively stable cyclic response at low total strain amplitudes. At higher total strain amplitudes, cyclic softening from the onset of deformation was obsd. However, the presence of Al3Ti blocks led to a very slight cyclic hardening followed by softening at total strain amplitude of 0.4%. Moreover, the intermetallic Al3Ti blocks reduced the fatigue life of in situ composites as they promoted microscopic cracking during cyclic deformation. Finally, the fatigue life data of in situ composites can be described by the Coffin-Manson relationship.
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    Nickel composite coatings were prepd. on mild steel substrates by sediment electro-co-deposition (SECD) technique. Silicon nitride, fly ash and calcium fluoride are used as the reinforcements. Metallog. studies, microhardness, friction and wear tests under various loads and sliding speeds were carried out on these coatings. Optical and SEM studies on the worn surfaces were conducted. A theor. model was used to predict the wear rates of the composite coatings. All the composite coatings exhibited a lower coeff. of friction and better wear resistance when compared with nickel coatings at all loads and sliding velocities studied. However, nickel-calcium fluoride composite coatings possessed the lowest coeff. of friction and wear rates. Significant effect of load and sliding speed on both the coeff. of friction and wear rates of nickel, nickel-silicon nitride and nickel-fly ash coatings was obsd. SEM studies of the worn surfaces reveal delamination process at higher loads. The predicted wear rates are in reasonable agreement with the exptl. values.
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  • Abstract

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    Figure 1

    Figure 1. (a–d) SEM images of Al2014–Al2O3p composites with different composition of CPS (83 μm) alumina particulates: (a) as-cast Al2014 alloy, (b) Al2014–9 wt % Al2O3p, (c) Al2014–12 wt % Al2O3p, and (d) Al2014–15 wt % Al2O3p. (e–g) SEM images of Al2014–Al2O3p composites with a different composition of IPS (53 μm) alumina particulates: (e) Al2014–9 wt % Al2O3p, (f) Al2014–12 wt % Al2O3p, and (g) Al2014–15 wt % Al2O3p. (h–j) SEM images of Al2014–Al2O3p composites with different compositions of FPS (20 μm) alumina particulates: (h) Al2014–9 wt % Al2O3p, (i) Al2014–12 wt % Al2O3p, and (j) Al2014–15 wt % Al2O3p.

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    Figure 2

    Figure 2. Particle size impact on microhardness measurements of base alloy and produced composites with variable particle size and weight fractions.

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    Figure 3

    Figure 3. (a) UTS, (b) YS, and (c) percentage elongation of base alloy and produced composites with variable particle size (FPS, IPS, and CPS) of alumina at different compositions (9, 12, and 15 wt %)

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    Figure 4

    Figure 4. (a–h) Fractographic of images of (a, b) Al2014 and (c–h) Al2014–15 wt % Al2O3 with CPS, IPS, and FPS and at different magnifications.

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    Figure 5

    Figure 5. (a, b) Volumetric wear results of CPS, IPS, and FPS variations of synthesized composites (a) for different load conditions and (b) for different sliding distance conditions.

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    Figure 6

    Figure 6. (a–h) Worn surface images of CPS, IPS, and FPS variation of Al2014–15 wt % Al2O3p composites. (e–h) Wear debris images of CPS, IPS and FPS variation of Al2014–15 wt % Al2O3p composites.

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  • References

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      Zhang, Z. F.; Zhang, L. C.; Mai, Y. W.
      Journal of Materials Science (1995), 30 (8), 1961-6CODEN: JMTSAS; ISSN:0022-2461. (Chapman & Hall)
      Pin-on-disk dry sliding tests were carried out to study the wear mechanisms in a range of metal-matrix composites. 6061-Aluminum alloys reinforced with 10 and 20 vol% SiC and Al2O3 particles were used as pin materials, and a mild steel disk was used as a counterface. A transition from mild wear to severe wear was found for the present composites; the wear rate increased by a factor of 102. The effects of the ceramic particles on the transition load and wear with varying normal pressure were thoroughly investigated. Three wear mechanisms were identified: abrasion in the running-in period, oxidn. during steady wear at low load levels, and adhesion at high loads. A higher particle vol. fraction raised the transition load but increased the wear rate in the abrasion and adhesion regimes. Increase of particle size was more effective than increase of vol. fraction to prolong the transition from mild wear to adhesive wear. The reasons for different wear mechanisms were detd. by analyses of the worn surfaces and wear debris.
    15. 15
      Khatri, S.; Koczak, M. Formation of TiC in in situ processed composites via solid-gas, solid-liquid and liquid-gas reaction in molten Al-Ti. Mater. Sci. Eng.A 1993, 162, 153– 162,  DOI: 10.1016/0921-5093(90)90040-A
      There is no corresponding record for this reference.
    16. 16
      Das, S.; Prasad, S. V.; Ramachandran, T. R. Microstructure and wear of cast (Al-Si alloy)-graphite composites. Wear. 1989, 133, 173– 187,  DOI: 10.1016/0043-1648(89)90122-1
      16
      Microstructure and wear of cast (aluminum-silicon alloy)-graphite composites
      Das, S.; Prasad, S. V.; Ramachandran, T. R.
      Wear (1989), 133 (1), 173-87CODEN: WEARAH; ISSN:0043-1648.
      LM13 of near-eutectic and LM30 of hypereutectic compn. were chosen as matrix alloys. Composites and matrix alloys were heat treated to produce different morphols. of Si ranging from platelike in die-cast alloys to near spherical in heat-treated alloys. Wear tests were conducted under dry and partially lubricated conditions with SAE30 oil on a pin-on-disk wear test app. against a rotating steel EN25 counterbody. In partially lubricated wear tests, the sliding velocity was 1.4-4.6 m/s, and the applied pressure was 1.0-5.0 MPa. The pressure-velocity limits of all matrix alloys and composites with different microstructures were evaluated. Heat-treated composites possess superior wear rate, seizure resistance, and pressure-velocity limits as compared with those of die-cast composites and matrix alloys. Worn surfaces of heat-treated composites showed a graphite film, while those of die-cast alloys and composites showed surface fracture. The role of graphite particle dispersion and morphol. of Si on the sliding wear is discussed.
    17. 17
      Ramesh, C. S.; Keshavamurthy, R.; Channabasappa, B. H.; Pramod, S. Friction and wear behavior of Ni–P coated Si3N4 reinforced Al6061 composites. Tribol. Int. 2010, 43, 623– 634,  DOI: 10.1016/j.triboint.2009.09.011
      17
      Friction and wear behavior of Ni-P coated Si3N4 reinforced Al6061 composites
      Ramesh, C. S.; Keshavamurthy, R.; Channabasappa, B. H.; Pramod, S.
      Tribology International (2010), 43 (3), 623-634CODEN: TRBIBK; ISSN:0301-679X. (Elsevier Ltd.)
      Al6061 matrix composite reinforced with nickel coated silicon nitride particles were manufd. by liq. metallurgy route. Microstructure and tribol. properties of both matrix alloy and developed composites have been evaluated. Dry sliding friction and wear tests were carried out using pin on disk type machine over a load range of 20-100 N and sliding velocities of range 0.31-1.57 m/s. Results revealed that, nickel coated silicon nitride particles are uniformly distributed through out the matrix alloy. Al6061-Ni-P-Si3N4 composite exhibited lower coeff. of friction and wear rate compared to matrix alloy. The coeff. of friction of both matrix alloy and developed composite decreased with increase in load up to 80 N. Beyond this, with further increase in the load, the coeff. of friction increased slightly. However, with increase in sliding velocity coeff. of friction of both matrix alloy and developed composite increases continuously. Wear rates of both matrix alloy and developed composites increased with increase in both load and sliding velocity. Worn surfaces and wear debris was examd. using SEM for possible wear mechanisms. Energy dispersive spectroscope (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) techniques were used to identify the oxides formed on the worn surfaces and wear debris.
    18. 18
      Tung, S. C.; McMillan, M. L. Automotive tribology overview of current advances and challenges for the future. Tribol. Int. 2004, 37, 517– 536,  DOI: 10.1016/j.triboint.2004.01.013
      18
      Automotive tribology overview of current advances and challenges for the future
      Tung, Simon C.; McMillan, Michael L.
      Tribology International (2004), 37 (7), 517-536CODEN: TRBIBK; ISSN:0301-679X. (Elsevier Ltd.)
      A review. This keynote address will provide a comprehensive overview of various lubrication aspects of a typical powertrain system including the engine, transmission, driveline, and other components, as well as the integration of these lubrication and surface engineering concepts into a unified automotive powertrain system. In addn., this presentation will focus on the current status and future trends in automotive lubricants including discussion of current and anticipated future requirements of automotive engine oils. This presentation will also review the current std. ASTM (American Society for Testing and Materials) test methods for engine lubricants and other compilations of automotive stds. In addn. to engine oil test development, industrial researchers are developing light-wt. materials such as non-ferrous materials (Al, Mg) for engine and drivetrain materials to replace the current heavy-wt. cast iron blocks. Recent industrial developments include high strength and high d. of composite materials, high vol. liq. molding and hydroforming technol., structural adhesive boding, and the ability to mold large structural components. Industrial researchers have also developed processing improvements for forming more complex stamped aluminum parts or panels, more robust stamping, and improved casting techniques. In this paper, our insights and perspectives on future trends in light-wt. tribol. material and nonotribol. will also be reviewed.
    19. 19
      Ceschini, L.; Minak, G.; Morri, A. Tensile and fatigue properties of the AA6061/20 vol% Al2O3p and AA7005/10 vol% Al2O3p composites. Compos. Sci. Technol. 2006, 66, 333– 342,  DOI: 10.1016/j.compscitech.2005.04.044
      19
      Tensile and fatigue properties of the AA6061/20vol.% Al2O3p and AA7005/10vol.% Al2O3p composites
      Ceschini, L.; Minak, G.; Morri, A.
      Composites Science and Technology (2006), 66 (2), 333-342CODEN: CSTCEH; ISSN:0266-3538. (Elsevier B.V.)
      In this paper, the tensile properties and the low-cycle fatigue behavior of the 7005 aluminum alloy reinforced with 10 vol% of Al2O3 particles (W7A10A composite) and 6061 aluminum alloy reinforced with 20 vol% of Al2O3 particles (W6A20A composite) were studied. The microstructural analyses showed clustering of Al2O3 particles, irregularly shaped and with a non-uniform size. A significant increase of the elastic modulus and tensile strength in the MMCs, respect to the unreinforced alloys, was evidenced by the tensile tests, while the elongation to fracture decreased. The temp. effect on the tensile properties was not relevant up to 150°C, while strength significantly decreased at 250°C, mainly in the composite with the lower content of the ceramic reinforcement. The low-cycle fatigue tests showed no evidence of isotropic hardening or softening for the W7A10A, and a slight cyclic softening for the W6A20A. SEM analyses of the fracture surfaces showed that both the tensile and fatigue fracture was controlled by interfacial decohesion (expecially for the W7A10A composite), fracture of reinforcing particles (mainly for the W6A20A composite), void nucleation and growth. Also the presence of the MgAl2O4 spinel, probably, played a significant role in the mechanisms of failure in the W6A20A composite, by promoting void nucleation at the particles-matrix interfaces, interfacial decohesion, and also failure of the particles. These effects can be responsible of the slight softening obsd. in the W6A20A, under the low-cycle fatigue conditions.
    20. 20
      Doel, T. J. A.; Bowen, P. Tensile properties of particulate-reinforced metal matrix composites. Composites, Part A 1996, 27, 655– 665,  DOI: 10.1016/1359-835X(96)00040-1
      20
      Tensile properties of particulate-reinforced metal matrix composites
      Doel, T. J. A.; Bowen, P.
      Composites, Part A: Applied Science and Manufacturing (1996), 27A (8), 655-665CODEN: CASMFJ; ISSN:1359-835X. (Elsevier)
      Room temp. tensile tests have been carried out on MMCs, all based on the Al alloy 7075 and on monolithic material. The particulate reinforcements used were SiC in three nominal sizes, 5, 13 and 60 μm. Three matrix aging conditions were studied, peak aged and equiv. underaged and overaged matrix conditions, based on microhardness measurements. The effects of aging condition on the tensile properties of the composites follow those produced in unreinforced material. Composites contg. 5 and 13 μm particles both had greater 0.2% proof stress and tensile strength values than unreinforced material. However, the composite reinforced with 60 μm particles had reduced 0.2% proof stress and tensile strength in the underaged and peak aged condition, and a greater 0.2% proof stress in the overaged condition compared to the monolithic alloy. All the composites had lower ductility than the unreinforced material, with the material contg. 5 μm SiC being the most ductile and that reinforced with 60 μm SiC having very low ductility. Failure appears to occur by the accumulation of internal damage to particles either by particle fracture or interfacial failure. Such damage introduces voids which grow and lead to reduced ductility in these composites. Large 60 μm particles fracture easily at low applied stresses, leading to reduced 0.2% proof stress and premature failure compared to the other composites. The small 5 and 13 μm particles damage less easily and so these composites are stronger than the monolithic material and are more ductile than the composite reinforced with 50 μm particles.
    21. 21
      Hong, S. J.; Kim, H. M.; Huh, D.; Suryanarayana, C.; Chun, B. S. Effect of clustering on the mechanical properties of SiC particulate-reinforced aluminum alloy 2024 metal matrix composites. Mater. Sci. Eng., A 2003, 347, 198– 204,  DOI: 10.1016/S0921-5093(02)00593-2
      21
      Effect of clustering on the mechanical properties of SiC particulate-reinforced aluminum alloy 2024 metal matrix composites
      Hong, Soon-Jik; Kim, Hong-Moule; Huh, Dae; Suryanarayana, C.; Chun, Byong Sun
      Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing (2003), A347 (1-2), 198-204CODEN: MSAPE3; ISSN:0921-5093. (Elsevier Science B.V.)
      Al 2024/SiC metal matrix composite powders produced by centrifugal atomization were hot extruded to investigate the effect of clustering on their mech. properties. Fracture toughness and tensile tests were conducted on specimens reinforced with 3-10 vol.% SiC. A model was proposed to suggest that the strength of the composite can be estd. from the load transfer model approach that takes into consideration the extent of clustering. This model has been successful in predicting the exptl. obsd. strength and fracture toughness values of the Al 2024-SiC composites. On the basis of exptl. observations, the strength of particulate-reinforced composites may be calcd. from the relation σy = σmVm + σr(Vr-Vc) - σrVc, where σ and V represent the yield strength and vol. fraction, resp., and the subscripts m, r, and c represent the matrix, reinforcement, and clusters, resp.
    22. 22
      Al-Qutub, A. M.; Allam, I. M.; Qureshi, T. W. Wear properties of 10% sub-micron Al2O3/6061 aluminium alloy composite. Int. J. Appl. Mech. Eng. Mech. 2002, 7, 329– 334
      22
      Wear properties of 10% sub-micron AL2O3/6061 aluminum alloy composite
      Al-Qutub, A. M.; Allam, I. M.; Qureshi, T. W.
      International Journal of Applied Mechanics and Engineering (2002), 7 (Spec. Issue), 329-334CODEN: IJAMAJ ISSN:. (University of Zielona Gora)
      The effect of reinforcing 6061 Aluminum alloy with 10% sub-micron Al2O3 by vol. on the wear properties was studied using a pin-on-disk type tribometer as well as Vickers micro-Hardness tester. The dry wear test, for the alloy and the composite, was performed at room temp. under different loads with a relative speed of 1 m/s. The pin was either made of the 6061 alloy or the composite. The counter face was made of AISI 4140 tool steel disk. Three wear mechanisms were obsd.: abrasion, surface fatigue, and adhesion. Almost all wear mechanisms were obsd. in combination under different loads. However, abrasion was dominant at low loads, delamination wear was dominant at higher loads and adhesion was more clear at extreme loads. The presence of sub-micron Al2O3 particles in the composite increased both hardness and wear resistance. Depending on the load, the wear resistance increased by 20% to 106% with the ceramic reinforcement. Also, the transition load, from mild to sever wear, was increased due to the addn. of the ceramic.
    23. 23
      Kouzeli, M.; Dunand, D. C. Effect of reinforcement connectivity on the elasto-plastic behavior of aluminum composites containing sub-micron alumina particles. Acta Mater. 2003, 51, 6105– 6121,  DOI: 10.1016/S1359-6454(03)00431-2
      23
      Effect of reinforcement connectivity on the elasto-plastic behavior of aluminum composites containing sub-micron alumina particles
      Kouzeli, M.; Dunand, D. C.
      Acta Materialia (2003), 51 (20), 6105-6121CODEN: ACMAFD; ISSN:1359-6454. (Elsevier Ltd.)
      The mech. properties of composites consisting of an aluminum matrix with 34 and 37 vol.% sub-micron Al2O3 particles were studied in compression for two reinforcement architectures: interconnected and discontinuous. Both the elastic and plastic behaviors of these composites are successfully modeled using a self-consistent approach: the classical self-consistent and the three-phase self-consistent models for the interconnected and discontinuous architectures, resp. At ambient temp., an interconnected architecture offers only a modest increase in stiffness and strength over a discontinuous architecture of equal vol. fraction. At elevated temps. (250, 500 and 600 °C), the interconnected reinforcement becomes increasingly more effective at strengthening the composites. However, the relative increase in strength due to interconnectivity can only be exploited at small strains (1-5%) due to the early development of compressive flow instabilities in the interconnected composites. While microstructural damage controls the instability strain of the interconnected composites at ambient temp., their low strain-hardening coeff. is the main contribution to flow instabilities at elevated temp.
    24. 24
      Wang, X.; Wu, G.; Sun, D.; Qin, C.; Tian, Y. Micro-yield property of sub-micron Al2O3 particle reinforced 2024 aluminum matrix composite. Mater. Lett. 2004, 58, 333– 336,  DOI: 10.1016/S0167-577X(03)00481-6
      There is no corresponding record for this reference.
    25. 25
      Ray, S. Synthesis of cast metal matrix particulate composites. J. Mater. Sci. 1993, 28, 5397– 5413,  DOI: 10.1007/BF00367809
      25
      Synthesis of cast metal matrix particulate composites
      Ray, S.
      Journal of Materials Science (1993), 28 (20), 5397-413CODEN: JMTSAS; ISSN:0022-2461.
      The present review with 67 refs. begins by briefly tracing history in the early days of development of cast metal-matrix composites and also outlines different casting routes for their synthesis. The problems faced by the quality of cast products and their relation to the process variables and characteristics of a given process, constitute the main theme of the review. The development of microstructure was discussed in view of nucleation behavior anticipated on the basis of estd. interface energies. The solidification around dispersoids and in regions away from it was highlighted. Porosity in cast composites (its origin and control in cast components by suitable mold design) has engaged attention because of damage to mech. properties due to porosity. The chem. reactions at the interface between dispersoid and matrix during processing of certain important systems of composites, were described and the means of controlling these reactions were indicated. The review concludes by drawing attention to the potential for application of cast composites in different industrial components and underlines the necessity of research in certain related fields so that industrial application of cast metal-matrix composites will soon become a reality.
    26. 26
      Prabhavalkar, Y.; Chapgaon, A. N. Effect of volume fraction of Al2O3 on tensile strength of aluminium 6061 by varying stir casting furnace parameters: A review. Int. Res. J. Eng. Technol. 2017, 4, 1351– 1355
      There is no corresponding record for this reference.
    27. 27
      Mazahery, A.; Shabani, M. O. Microstructural and abrasive wear properties of SiC reinforced aluminum-based composite produced by compocasting. Trans. Nonferrous Met. Soc. China 2013, 23, 1905– 1914,  DOI: 10.1016/S1003-6326(13)62676-X
      27
      Microstructural and abrasive wear properties of SiC reinforced aluminum-based composite produced by compocasting
      Mazahery, Ali; Shabani, Mohsen Ostad
      Transactions of Nonferrous Metals Society of China (2013), 23 (7), 1905-1914CODEN: TNMCEW; ISSN:1003-6326. (Elsevier B.V.)
      The effect of SiC particles reinforcement with av. size of 1, 5, 20 and 50 μm and vol. fraction of 5%, 10% and 15% on the microstructure and tribol. properties of Al-based composite was investigated. Composites were produced by applying compocasting process. Tribol. properties of the unreinforced alloy and composites were studied using pin-on-disk wear tester, under dry sliding conditions at different specific loads. The influence of secondary mech. processing with different rolling redns. on the dry sliding wear characteristics of Al matrix composites was also assessed. Hardness measurement and SEM were used for microstructural characterization and investigation of worn surfaces and wear debris. The proper selection of process parameter such as pouring temp., stirring speed, stirring time, pre-heated temp. of reinforcement can all influence the quality of the fabricated composites. The porosity level of composite should be minimized and the chem. reaction between the reinforcement and matrix should be avoided.
    28. 28
      Bharath, V.; Ajawan, S. S.; Nagaral, M.; Auradi, V.; Kori, S. A. Characterization and Mechanical Properties of 2014 Aluminum Alloy Reinforced with Al 2 O 3p Composite Produced by Two-Stage Stir Casting Route. J. Inst. Eng. (India): Ser. C 2019, 100, 277– 282,  DOI: 10.1007/s40032-018-0442-x
      There is no corresponding record for this reference.
    29. 29
      Auradi, V.; Rajesh, G. L.; Kori, S. A. Processing of B4C Particulate Reinforced 6061Aluminum Matrix Composites by melt stirring involving two-step addition. Procedia Mater. Sci. 2014, 6, 1068– 1076,  DOI: 10.1016/j.mspro.2014.07.177
      29
      Processing of B4C Particulate Reinforced 6061Aluminum Matrix Composites by Melt Stirring Involving Two-step Addition
      Auradi, V.; Rajesh, G. L.; Kori, S. A.
      Procedia Materials Science (2014), 6 (), 1068-1076CODEN: PMSREM; ISSN:2211-8128. (Elsevier B.V.)
      In the present work, 11wt% B4C particulate reinforced 6061 Al matrix composites were produced by conventional melt stirring method. Processing of composite is carried out at a temp. of 750 °C involving two stage addns. Preheated B4C particles along with K2TiF6 halide salt (with ratio of 0.3) was introduced in steps of two rather than adding all at once. Characterization of the prepd. composites is done using SEM/EDX and X-RD studies. Fairly uniform distribution of B4C particulates without clustering in 6061Al matrix was evident from SEM studies. The prepd. composite consists of α-Al, B4C and minor phases like Al3Ti, AlB2 and Al3BC are confirmed by XRD studies. The addn. of B4C particulates to 6061Al matrix has resulted in improvements in mech. properties of the base alloy.
    30. 30
      Sajjadi, S. A.; Ezatpour, H. R.; Parizi, M. T. Comparison of microstructure and mechanical properties of A356 aluminum alloy/Al2O3 composites fabricated by stir and compo-casting processes. Mater. Des. 2012, 34, 106– 111,  DOI: 10.1016/j.matdes.2011.07.037
      30
      Comparison of microstructure and mechanical properties of A356 aluminum alloy/Al2O3 composites fabricated by stir and compo-casting processes
      Sajjadi, S. A.; Ezatpour, H. R.; Torabi Parizi, M.
      Materials & Design (2012), 34 (), 106-111CODEN: MADSD2; ISSN:0264-1275. (Elsevier Ltd.)
      Metal-matrix composites (MMCs), as light and strong materials, are very attractive for application in different industries. In the present work, nano and micro-composites (A356/Al2O3) with different wt. percent of particles were fabricated by two melt techniques such as stir-casting and compo-casting. Microstructural characterization was investigated by optical (OP) and SEM. Tensile, hardness and compression tests were carried out in order to identify mech. properties of the composites. The results of microstructural study revealed uniform distribution, grain refinement and low porosity in micro and nano-composite specimens. The mech. results showed that the addn. of alumina (micro and nano) led to the improvement in yield strength, ultimate tensile strength, compression strength and hardness. It was indicated that type of fabrication process and particle size were the effective factors influencing on the mech. properties. Decreasing alumina particle size and using compo-casting process obtained the best mech. properties.
    31. 31
      Zulfia, A.; Putro, E. C.; Wahyudi, M.; Dhaneswara, D.; Utomo, B. W. Fabrication and characteristics of ADC-12 reinforced nano-SiC and nano-Al2O3 composites through stir casting route. IOP Conf. Ser.: Mater. Sci. Eng. 2018, 432, 012032,  DOI: 10.1088/1757-899X/432/1/012032
      31
      Fabrication and characteristics of ADC-12 reinforced nano-SiC and nano-Al2O3 composites through stir casting route
      Zulfia, A.; Putro, E. C.; Wahyudi, M.; Dhaneswara, D.; Utomo, B. W.
      IOP Conference Series: Materials Science and Engineering (2018), 432 (1st Materials Research Society Indonesia Conference and Congress, 2017), 012032/1-012032/8CODEN: ICSMGW; ISSN:1757-899X. (IOP Publishing Ltd.)
      Aluminum ADC-12 reinforced with nano-SiC and nano-Al2O3 have been successfully produced by stir casting method. The effect of addn. nano SiC and Al2O3 into matrix has been studied with variation of 0.05, 0.10, 0.15, 0.20, 0.30 vf-% for each composites. The addn. of Mg was introduced with 10 wt-% to promote wetting between molten Al and ceramic particle reinforcement. The OES result shows decreasing amt. of excess Si and Mg in the composite compared to as-cast ADC-12. One of the main intermetallic phases present evenly in aluminum matrix is Mg2Si which was confirmed by EDS and XRD. The highest tensile strength and hardness of composites were achieved by the addn. of 0.15 and 0.30%vf SiC and Al2O3, resp., with the values of 111 and 115 MPa and 42 and 41 HRB. The increasing hardness generated significant improvement in wear resistance of composites. The higher the reinforcement content, the higher the porosity formed, due to the tendency of dewetting as well as nano particles agglomeration.
    32. 32
      Kumar, B. P.; Birru, A. K. Microstructure and mechanical properties of aluminium metal matrix composites with addition of bamboo leaf ash by stir casting method. Trans. C. Soc. China 2017, 27, 2555– 2572,  DOI: 10.1016/S1003-6326(17)60284-X
      There is no corresponding record for this reference.
    33. 33
      Liu, X.; Zhang, P.; He, S.; Xu, Q.; Dou, Z.; Wang, H. Effect of beryllium content and heat treatment on microstructure and yield strength in Be/6061Al composites. J. Alloys Compd. 2018, 743, 746– 755,  DOI: 10.1016/j.jallcom.2018.02.060
      33
      Effect of beryllium content and heat treatment on microstructure and yield strength in Be/6061Al composites
      Liu, Xiangdong; Zhang, Pengcheng; He, Shixiong; Xu, Qingdong; Dou, Zuoyong; Wang, Haijun
      Journal of Alloys and Compounds (2018), 743 (), 746-755CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)
      6061Al alloy was selected as the matrix of beryllium-aluminum composites and Be/6061Al composites with 20wt% Be, 40 wt% Be and 62 wt%Be were prepd. by hot isostatic pressing sintering technol. The microstructure and interface characteristics of Be/6061Al composites were investigated and characterized by SEM and TEM. The results showed that Be/6061Al composites were made up of Be phase and Al rich phase and there was no reaction product at the interface. Be phase and Al-rich phase combined mech. and kept a certain orientation relationship in Be/6061Al composite. The yield strength of Be/6061Al composites increased with the increase of Be content, which could be predicted by modified shear lag model. Mg and Si formed β'' and pptd. in the Al matrix after artificially aging treatment and dramatically improved the yield strength of Be/6061Al composites.
    34. 34
      Mohanavel, V.; Rajan, K.; Kumar, S. S.; Vijayan, G.; Vijayanand, M. S. Study on mechanical properties of graphite particulates reinforced aluminium matrix composite fabricated by stir casting technique. Mater. Today: Proc. 2018, 5, 2945– 2950,  DOI: 10.1016/j.matpr.2018.01.090
      34
      Study on mechanical properties of graphite particulates reinforced aluminum matrix composite fabricated by stir casting technique
      Mohanavel, V.; Rajan, K.; Suresh Kumar, S.; Vijayan, G.; Vijayanand, M. S.
      Materials Today: Proceedings (2018), 5 (1_Part_3), 2945-2950CODEN: MTPAC4; ISSN:2214-7853. (Elsevier Ltd.)
      The lineage of applied materials science is always in demand for light wt. and highly performing materials. Such materials would find their applications in aircraft, structural, non-structural and automobile industries, etc. The present research study focuses on the prodn. of aluminum (AA6351) matrix composites reinforced in different mass fractions of graphite particulates by using stir casting method. The mass fraction of reinforcement was varied from 0% to 12% in stages of 4%. Hardness and tensile strength of the composite were investigated. The microstructures of the produced composites were examd. by scanning electron microg. test. The SEM images revealed the non-homogeneous distribution of graphite (Gr) particles in the matrix and this may be due to low d. of graphite. The test results revealed that the mech. properties of the composite decrease with increase in the mass fraction of graphite particle content, this may be due to poor interfacial bonding between the reinforcement and the matrix. The brittle nature of the reinforcing particles (graphite) plays a vital role in decreasing the mech. properties because the graphite as a soft reinforcement is brittle in nature and so it enhanced the brittleness in the AMCs.
    35. 35
      Sharma, V. K.; Singh, R. C.; Chaudhary, R. Effect of flyash particles with aluminium melt on the wear of aluminium metal matrix composites. JESTECH. 2017, 20, 1318– 1323,  DOI: 10.1016/j.jestch.2017.08.004
      There is no corresponding record for this reference.
    36. 36
      Sekar, K.; Kanjirathikal, A.; Joseph, M. A. Effect of T6 Heat Treatment in Tribological Properties of A356 Aluminum Alloy Reinforced with Al2O3 Nanoparticles by Combination Effect of Stir and Squeeze Casting Method. Appl. Mech. Mater. 2014, 592, 968– 971,  DOI: 10.4028/www.scientific.net/AMM.592-594.968
      36
      Effect of T6 heat treatment in tribological properties of A356 aluminum alloy reinforced with Al2O3 nano particles by combination effect of stir and squeeze casting method
      Sekar, K.; Allesu, K.; Joseph, M. A.
      Applied Mechanics and Materials (2014), 592-594 (Dynamics of Machines and Mechanisms, Industrial Research), 968-971CODEN: AMMPDO; ISSN:1662-7482. (Trans Tech Publications Ltd.)
      A356 alloys are attractive alternative for automotive and aeronautical applications. In this work the effects of T6 heat treatment in tribol. properties of A356 alloy reinforced with Al2O3 nano particles of size 30nm are investigated. The percentage inclusions Al2O3 were varied from 0.5 to 1.5wt%. The particles were added with stirring at 400rpm and squeeze casting at 750°C and pressure of 600MPa in the squeeze casting machine. The tribol. properties of the samples were also investigated by pin-on-disk tests at 10,30,50and 70N, sliding speed 0.534m/s and sliding distance 1100m in dry condition. The lowest dry wear rate obtained through T6 heat treatment condition.
    37. 37
      Kok, M. Production and mechanical properties of Al2O3 particle-reinforced 2024 aluminium alloy composites. J. Mater. Process. Technol. 2005, 161, 381– 387,  DOI: 10.1016/j.jmatprotec.2004.07.068
      37
      Production and mechanical properties of Al2O3 particle-reinforced 2024 aluminium alloy composites
      Kok, M.
      Journal of Materials Processing Technology (2005), 161 (3), 381-387CODEN: JMPTEF; ISSN:0924-0136. (Elsevier B.V.)
      2024 Aluminum alloy metal matrix composites (MMCs) reinforced with three different sizes and wt. fractions of Al2O3 particles up to 30 wt.% were fabricated by a vortex method and subsequent applied pressure. The effects of Al2O3 particle content and size of particle on the mech. properties of the composites such as hardness and tensile strength were investigated. The d. measurements showed that the samples contained little porosity, and the amt. of porosity in the composites increased with increasing wt. fraction and decreasing size of particles. Scanning electron microscopic observations of the microstructures revealed that the dispersion of the coarser sizes of particles was more uniform while finer particles led to agglomeration of the particles and porosity. The results show that the hardness and the tensile strength of the composites increased with decreasing size and increasing wt. fraction of particles.
    38. 38
      Şahin, Y.; Öksüz, K. E. The Microstructure and Hardness of Al2O3 Particle Reinforced Composite. Appl. Mech. Mater. 2012, 232, 39– 44,  DOI: 10.4028/www.scientific.net/AMM.232.39
      38
      The microstructure and hardness of Al2O3 particle reinforced composite
      Sahin, Y.; Oksuz, K. Emre
      Applied Mechanics and Materials (2012), 232 (Mechanical and Aerospace Engineering), 39-44CODEN: AMMPDO; ISSN:1660-9336. (Trans Tech Publications Ltd.)
      Aluminum alloys (Al2014 and Al2124 alloy) and their composites contg. 10wt.% Al2O3 with 3 μm and 43 μm sizes of particles have been produced by powder metallurgy (PM) method and the microstructure and hardness were investigated. SEM investigation showed a nearly uniform distribution of the Al2O3 particles within the Al2124 alloy matrix although some porosities were found in the Al2014 alloy matrix. Furthermore, it was found that the macrohardness of Al2124 alloy composite improved highly in comparison to that of Al2014 alloy due to fine of microstructure and increased hardness. The hardnesses of both MMCs increased with increasing the particle sizes.
    39. 39
      Umanath, K.; Selvamani, S. T.; Palanikumar, K.; Raphael, T.; Prashanth, K. Effect of sliding distance on dry sliding wear behaviour of Al6061/SiC/Al2O3 hybrid composite. Proc. Int. Conf. Advances Mechanical Engineering 2013, 749– 756
      There is no corresponding record for this reference.
    40. 40
      Tian, K.; Zhao, Y.; Jiao, L.; Zhang, S.; Zhang, Z.; Wu, X. Effects of in situ generated ZrB2 nano-particles on microstructure and tensile properties of 2024Al matrix composites. J. Alloys Compd. 2014, 594, 1– 6,  DOI: 10.1016/j.jallcom.2014.01.117
      40
      Effects of in situ generated ZrB2 nano-particles on microstructure and tensile properties of 2024Al matrix composites
      Tian, Kangle; Zhao, Yutao; Jiao, Lei; Zhang, Songli; Zhang, Zhenya; Wu, Xiuchuan
      Journal of Alloys and Compounds (2014), 594 (), 1-6CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)
      The main purpose of this paper is to investigate the effects of nano-size ZrB2 particles on the microstructure and tensile properties of 2024Al matrix composites. The microstructure and tensile properties of the 2024Al matrix composites reinforced by ZrB2 nano-particles fabricated from 2024Al-K2ZrF6-KBF4 system by direct melt reaction are investigated by XRD, OM, SEM, EDS, TEM and tensile testing. The results reveal that the ZrB2 nano-particles exhibit rectangular and nearly hexagon shape with the size ranging from 30 to 100 nm, and the reasonable uniform distribution of ZrB2 nano-particles gives rise to significant grain refinement of 2024Al alloy. Tensile testing results show that the tensile strength and yield stress of the composites increase continuously. However, the elongation of the composites increases almost linearly and declines later as the increasing of ZrB2 content. The fracture morphologies are in accord with corresponding ductility results. What's more, the strengthening mechanism of ZrB2 nano-particles is established.
    41. 41
      Harti, J. I.; Prasad, T. B.; Nagaral, M.; Jadhav, P.; Auradi, V. Microstructure and dry sliding wear behaviour of Al2219-TiC composites. Mater. Today: Proc. 2017, 4, 11004– 11009,  DOI: 10.1016/j.matpr.2017.08.058
      There is no corresponding record for this reference.
    42. 42
      Li, M.; Ma, K.; Jiang, L.; Yang, H.; Lavernia, E. J.; Zhang, L.; Schoenung, J. M. Synthesis and mechanical behavior of nanostructured Al 5083/n-TiB2 metal matrix composites. Mater. Sci. Eng.A 2016, 656, 241– 248,  DOI: 10.1016/j.msea.2016.01.031
      42
      Synthesis and mechanical behavior of nanostructured Al 5083/n-TiB2 metal matrix composites
      Li, Meijuan; Ma, Kaka; Jiang, Lin; Yang, Hanry; Lavernia, Enrique J.; Zhang, Lianmeng; Schoenung, Julie M.
      Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing (2016), 656 (), 241-248CODEN: MSAPE3; ISSN:0921-5093. (Elsevier B.V.)
      Nanostructured Al 5083-based composites with nano-TiB2 reinforcement particles were fabricated via cryomilling and spark plasma sintering (SPS). TEM observation revealed that the Al matrix consists of equiaxed nano-grains (av. size, ∼74 nm), and the reinforcement, TiB2 nanoparticles (n-TiB2), was distributed discretely and homogeneously in the Al matrix. The interface between the Al-matrix and n-TiB2 appears to be free of defects, and no obvious discontinuities were obsd. The composite exhibits a compressive strength of 817 MPa with 6.0% strain-to-failure. The strength is 20% higher than that of an equiv. SPS consolidated Al 5083 without reinforcement. Nanoindentation was used in our study to provide fundamental insight into the local microscopic mech. properties. The strengthening mechanisms of the composites are analyzed taking into account the grain boundaries, the Orowan strengthening from the n-TiB2 particles and dispersoids such as Al2O3, AlN and Al6Mn, as well as geometrically necessary dislocations induced in the matrix by the nano-TiB2 particles.
    43. 43
      Gilman, P. S. Discontinuously reinforced aluminum: Ready for the 1990s. JOM 1991, 43, 7– 15,  DOI: 10.1007/BF03221096
      There is no corresponding record for this reference.
    44. 44
      Ünlü, B. S. Investigation of tribological and mechanical properties Al2O3–SiC reinforced Al composites manufactured by casting or P/M method. Mater. Des. 2008, 29, 2002– 2008,  DOI: 10.1016/j.matdes.2008.04.014
      44
      Investigation of tribological and mechanical properties Al2O3-SiC reinforced Al composites manufactured by casting or P/M method
      Uenlue, Bekir Sadik
      Materials & Design (2008), 29 (10), 2002-2008CODEN: MADSD2; ISSN:0264-1275. (Elsevier Ltd.)
      In this study, Al based Al2O3 and SiC particle reinforced composite materials were manufd. by casting or P/M method. Tribol. properties of these composite materials were investigated by wearing with 10 N load and 50 rpm on a pin-on-disk wear test rig at dry conditions. Mech. properties were investigated. The effects of reinforce materials on tribol. and mech. properties were investigated. In addn. to that microstructure of these materials were investigated by optical and SEM microscope. Tribol. and hardness properties of composites significantly improved by the use of particle reinforced into Al.
    45. 45
      Ramachandra, M.; Abhishek, A.; Siddeshwar, P.; Bharathi, V. Hardness and wear resistance of ZrO2 nano particle reinforced Al nanocomposites produced by powder metallurgy. Procedia Mater. Sci. 2015, 10, 212– 219,  DOI: 10.1016/j.mspro.2015.06.043
      45
      Hardness and Wear Resistance of ZrO2 Nano Particle Reinforced Al Nanocomposites Produced by Powder Metallurgy
      Ramachandra, M.; Abhishek, A.; Siddeshwar, P.; Bharathi, V.
      Procedia Materials Science (2015), 10 (), 212-219CODEN: PMSREM; ISSN:2211-8128. (Elsevier B.V.)
      Nano particle reinforced Aluminum Nanocomposites are produced using Zirconium dioxide (n-ZrO2). Nano particles produced by soln. combustion method. Urea is used as fuel and then reinforcing into Aluminum matrix in different percentages by wt. using the powder metallurgy technique. The specimens prepd. are tested for their hardness and microstructure. The above mentioned properties were chosen due to the reinforcement added (n-ZrO2) which is known to have good toughness and hardness among other structural properties at room temp. The composites are tested for wear resistance by using pin on disk wear testing machine. Study of Wear mechanisms, Microstructure were performed on sintered specimens. Microstructure revealed near uniform distribution of n-ZrO2 particles with slight agglomeration. The microstructure also revealed good interfacial bond between matrix and n-ZrO2 particles. Incorporation of n-ZrO2 particles in aluminum matrix can lead to the prodn. of aluminum composites with improved hardness and wear resistance. These composites can find applications in automotive components like pistons, cylinder liners and connecting rods.
    46. 46
      Prabu, S. B.; Karunamoorthy, L.; Kathiresan, S.; Mohan, B. Influence of stirring speed and stirring time on distribution of particles in cast metal matrix composite. J. Mater. Process. Technol. 2006, 171, 268– 273,  DOI: 10.1016/j.jmatprotec.2005.06.071
      46
      Influence of stirring speed and stirring time on distribution of particles in cast metal matrix composite
      Prabu, S. Balasivanandha; Karunamoorthy, L.; Kathiresan, S.; Mohan, B.
      Journal of Materials Processing Technology (2006), 171 (2), 268-273CODEN: JMPTEF; ISSN:0924-0136. (Elsevier B.V.)
      In the present study, high silicon content aluminum alloy-silicon carbide metal matrix composite material, with 10%SiC were successfully synthesized, using different stirring speeds and stirring times. The microstructure of the produced composites was examd. by optical microscope and scanning electron microscope. The Brinell hardness test was performed on the composite specimens from base of the cast to top. The results revealed that stirring speed and stirring time influenced the microstructure and the hardness of composite. Microstructure anal. revealed that at lower stirring speed with lower stirring time, the particle clustering was more. Increase in stirring speed and stirring time resulted in better distribution of particles. The hardness test results also revealed that stirring speed and stirring time have their effect on the hardness of the composite. The uniform hardness values were achieved at 600 rpm with 10 min stirring. But beyond certain stir speed the properties degraded again. An attempt is made in this study to establish the trend between processing parameters such as stirring speed and stirring time with microstructure and hardness of composite.
    47. 47
      Singla, M.; Dwivedi, D. D.; Singh, L.; Chawla, V. Development of aluminium based silicon carbide particulate metal matrix composite. J. Miner. Mater. Charact. Eng. 2009, 8, 455– 467,  DOI: 10.4236/jmmce.2009.86040
      There is no corresponding record for this reference.
    48. 48
      Das, S.; Das, S.; Das, K. Abrasive wear of zircon sand and alumina reinforced Al–4.5 wt %Cu alloy matrix composites – A comparative study. Compos. Sci. Technol. 2007, 67, 746– 751,  DOI: 10.1016/j.compscitech.2006.05.001
      48
      Abrasive wear of zircon sand and alumina reinforced Al-4.5wt%Cu alloy matrix composites - A comparative study
      Das, Sanjeev; Das, Siddhartha; Das, Karabi
      Composites Science and Technology (2007), 67 (3-4), 746-751CODEN: CSTCEH; ISSN:0266-3538. (Elsevier B.V.)
      In the present investigation a comparative study on abrasive wear behavior of aluminum metal matrix composite reinforced with alumina and zircon sand particles has been carried out. Microstructures of the composites in as-cast condition show uniform distribution of particles and reveal better bonding in the case of zircon particles reinforced composite compared to that in alumina particles reinforced composite. Abrasive wear resistance of both the composites improves with the decrease in particle size. It is obsd. that the alumina particle reinforced composite shows relatively poor wear resistance property compared to zircon-reinforced composite.
    49. 49
      Youssef, Y. M.; Dashwood, R. J.; Lee, P. D. Effect of clustering on particle pushing and solidification behaviour in TiB2 reinforced aluminium PMMCs. Composites, Part A 2005, 36, 747– 763,  DOI: 10.1016/j.compositesa.2004.10.027
      49
      Effect of clustering on particle pushing and solidification behaviour in TiB2 reinforced aluminium PMMCs
      Youssef, Y. M.; Dashwood, R. J.; Lee, P. D.
      Composites, Part A: Applied Science and Manufacturing (2005), 36A (6), 747-763CODEN: CASMFJ; ISSN:1359-835X. (Elsevier)
      The behavior of titanium diboride particles in molten aluminum was investigated by conducting casting expts. at different cooling rates and particle addn. levels, starting with a master alloy contg. in situ formed TiB2 particles. The particle pushing/engulfment phenomena and particle clustering effects were studied for two matrix alloy systems, com. purity (CP) aluminum and an Al-4% Mg (A514) alloy. The crit. velocity, which is the solidification velocity below which the particles are pushed and above which they are engulfed, was calcd. The results were validated against the predictions of the models available in the literature. The assumptions, limitations and comparative success of the different models were discussed. The crit. velocity obsd. in CP-Al ranged between 4 and 8 μm/s at low particulate concn. (<1 vol%) and decreased to less than 2 μm/s for the high concn. of particles. In the case of A514, the crit. velocity was lower at the low particulate concn. (between 2 and 3 μm/s). The hypothesis that particle clustering could result in erroneous crit. velocity predictions was explored and it was concluded that particle clustering must be included for accurate prediction of particle pushing in these alloys.
    50. 50
      Nakae, H.; Wu, S. Engulfment of Al2O3 particles during solidification of aluminum matrix composites. Mater. Sci. Eng.A 1998, 252, 232– 238,  DOI: 10.1016/S0921-5093(98)00664-9
      50
      Engulfment of Al2O3 particles during solidification of aluminum matrix composites
      Nakae, Hideo; Wu, Shusen
      Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing (1998), A252 (2), 232-238CODEN: MSAPE3; ISSN:0921-5093. (Elsevier Science S.A.)
      Through the anal. of forces acting on the particles at the solid/liq. interface based on the interfacial energies, a new theor. particle transfer model is proposed. This model can predict the behavior of the particles at the interface. The main concept of this model is proved by the mutual wetting behavior among the solid, liq. and particle phases. If the contact angle at a solid/liq. interface and a particle is <90°, the particle can be engulfed into the solid, and if the contact angle is >90°, the particle would be pushed. This contact angle is measured by unidirectional solidification (UDS) expts. If solidification expts. were carried out for particle dispersed composites in a conventional UDS, the particles completely descended before freezing, therefore, a zone-UDS was used in the expt. In Al-Sr, Al-Ca and Al-Ce matrix composites, Al2O3 particles are pushed by the solid because the contact angles are >90°. On the other hand, in Al-12.6wt.%Si-Sr-Al2O3 composites alloyed with Ca, the Al2O3 particles are engulfed into the solid because the contact angle is <90°.
    51. 51
      Rao, R. N.; Das, S.; Mondal, D. P.; Dixit, G.; Devi, S. T. Dry sliding wear maps for AA7010 (Al–Zn–Mg–Cu) aluminium matrix composite. Tribol. Int. 2013, 60, 77– 82,  DOI: 10.1016/j.triboint.2012.10.007
      51
      Dry sliding wear maps for AA7010 (Al-Zn-Mg-Cu) aluminium matrix composite
      Rao, R. N.; Das, S.; Mondal, D. P.; Dixit, G.; Tulasi Devi, S. L.
      Tribology International (2013), 60 (), 77-82CODEN: TRBIBK; ISSN:0301-679X. (Elsevier Ltd.)
      Wear mechanism map for aluminum matrix composite helps in predicting and understanding different wear mechanisms in a material. It also identifies the crit. load and sliding speed for transition of one wear mechanism to other. In the present investigation, the wear coeff. is in the range of 10-4-10-5 which is at the boundary region between mild to severe wear. It is also obsd. from that there are four wear regimes; they are ultra mild wear, mild wear or oxidative wear, delamination wear and severe wear. All these facts are discussed on the basis of prevailing wear mechanism.
    52. 52
      Cruz, K. S.; Meza, E. S.; Fernandes, F. A.; Quaresma, J. M.; Casteletti, L. C.; Garcia, A. Dendritic arm spacing affecting mechanical properties and wear behavior of Al-Sn and Al-Si alloys directionally solidified under unsteady-state conditions. Metall. Mater. Trans. A 2010, 41, 972– 984,  DOI: 10.1007/s11661-009-0161-2
      52
      Dendritic Arm Spacing Affecting Mechanical Properties and Wear Behavior of Al-Sn and Al-Si Alloys Directionally Solidified under Unsteady-State Conditions
      Cruz, Kleber S.; Meza, Elisangela S.; Fernandes, Frederico A. P.; Quaresma, Jose M. V.; Casteletti, Luiz C.; Garcia, Amauri
      Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science (2010), 41A (4), 972-984CODEN: MMTAEB; ISSN:1073-5623. (Springer)
      Alloys of Al-Sn and Al-Si are widely used in tribol. applications such as cylinder liners and journal bearings. Studies of the influence of the as-cast microstructures of these alloys on the final mech. properties and wear resistance can be very useful for planning solidification conditions in order to permit a desired level of final properties to be achieved. The aim of the present study was to contribute to a better understanding about the relationship between the scale of the dendritic network and the corresponding mech. properties and wear behavior. The Al-Sn (15 and 20 wt pct Sn) and Al-Si (3 and 5 wt pct Si) alloys were directionally solidified under unsteady-state heat flow conditions in water-cooled molds in order to permit samples with a wide range of dendritic spacings to be obtained. These samples were subjected to tensile and wear tests, and exptl. quant. expressions correlating the ultimate tensile strength (UTS), yield tensile strength, elongation, and wear vol. to the primary dendritic arm spacing (DAS) have been detd. The wear resistance was shown to be significantly affected by the scale of primary dendrite arm spacing. For Al-Si alloys, the refinement of the dendritic array improved the wear resistance, while for the Al-Sn alloys, an opposite effect was obsd., i.e., the increase in primary dendrite arm spacing improved the wear resistance. The effect of inverse segregation, which is obsd. for Al-Sn alloys, on the wear resistance is also discussed.
    53. 53
      Murakami, T.; Kajino, S.; Nakano, S. High-temperature friction and wear properties of various sliding materials against aluminum alloy 5052. Tribol. Int. 2013, 60, 45– 52,  DOI: 10.1016/j.triboint.2012.10.015
      53
      High-temperature friction and wear properties of various sliding materials against aluminum alloy 5052
      Murakami, T.; Kajino, S.; Nakano, S.
      Tribology International (2013), 60 (), 45-52CODEN: TRBIBK; ISSN:0301-679X. (Elsevier Ltd.)
      The friction and wear properties of Si3N4-8mass% Al2O3-6mass% Y2O3, AISI H13 steel, AISI 52100 steel, Inconel 600, ZrO2-3 mol% Y2O3, WC-6mass% Co and BN-50mass% Ni disk specimens sliding against aluminum alloy 5052 were examd. at 823 K in air. The AISI H13 steel, AISI 52100 steel and BN-50mass% Ni disk specimens exhibited relatively stable friction coeffs. as low as 0.4-0.5, although the AISI 52100 steel and BN-50mass% Ni disk specimens exhibited the largest vol. increase and the highest specific wear rates, resp. On the other hand, the AISI H13 steel, ZrO2-3 mol% Y2O3 and WC-6mass% Co disk specimens exhibited much smaller vol. changes than AISI 52100 steel, Inconel 600 and BN-50mass% Ni disk specimens. However, the ZrO2-3 mol% Y2O3 and WC-6mass% Co disk specimens exhibited unstable friction coeffs. and the friction coeffs. as high as 0.6, resp. SEM-EDS analyses revealed large amt. of Al and oxygen on the worn surfaces of the Si3N4-8mass% Al2O3-6mass% Y2O3, AISI H13 steel, AISI 52100 steel and ZrO2-3 mol% Y2O3 disk specimens, while much smaller amt. of Al and oxygen were obsd. on the worn surfaces of the Inconel 600, WC-6mass% Co and BN-50mass% Ni disk specimens. In addn., distinct oxygen peaks were obsd. on the worn surfaces of all the aluminum alloy pin specimens, but such oxygen peaks were hardly obsd. on the non-worn surfaces of all the pin specimens.
    54. 54
      Mittal, P.; Dixit, G. Dry sliding wear behaviour of 2014 aluminium alloy reinforced with SiC composite. Int. J. Eng. Res. Sci. Technol. 2016, 5, 147– 153,  DOI: 10.17577/IJERTV5IS060172
      There is no corresponding record for this reference.
    55. 55
      Zhang, Z.; Chen, D. L. Contribution of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites. Mater. Sci. Eng.A 2008, 483, 148– 152,  DOI: 10.1016/j.msea.2006.10.184
      55
      Contribution of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites
      Zhang, Z.; Chen, D. L.
      Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing (2008), A483-A484 (), 148-152CODEN: MSAPE3; ISSN:0921-5093. (Elsevier B.V.)
      The relative contribution of three strengthening factors in particulate-reinforced metal matrix nanocomposites (MMNCs), namely, load-bearing effect, enhanced dislocation d. strengthening effect and Orowan strengthening effect, is evaluated. Orowan strengthening mechanism is found to play a significant role in MMNCs. The relative contribution of Orowan strengthening effect increases with decreasing size of nanoparticles. However, there exists a crit. particle size below which the Orowan strengthening effect drops abruptly. The crit. particle size, independent of the vol. fraction of nanoparticles, is found to be about 5.44 times the magnitude of the Burgers vector of dislocations in the matrix.
    56. 56
      Zhang, Z.; Chen, D. L. Consideration of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites: A model for predicting their yield strength. Scr. Mater. 2006, 54, 1321– 1326,  DOI: 10.1016/j.scriptamat.2005.12.017
      56
      Consideration of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites: a model for predicting their yield strength
      Zhang, Z.; Chen, D. L.
      Scripta Materialia (2006), 54 (7), 1321-1326CODEN: SCMAF7; ISSN:1359-6462. (Elsevier Ltd.)
      An anal. model for predicting the yield strength of particulate-reinforced metal matrix nanocomposites was developed. The strengthening effects involving (i) Orowan strengthening effect, (ii) enhanced dislocation d. due to the residual plastic strain caused by the difference in the coeffs. of thermal expansion between the matrix and particles and (iii) load-bearing effects were taken into account. The prediction is in good agreement with the exptl. data reported in the literature.
    57. 57
      Özdemir, I.; Önel, K. Thermal cycling behaviour of an extruded aluminium alloy/SiCp composite. Composites, Part B 2004, 35, 379– 384,  DOI: 10.1016/j.compositesb.2004.02.007
      57
      Thermal cycling behavior of an extruded aluminum alloy/SiCp composite
      Ozdemir, Ismail; Onel, Kazim
      Composites, Part B: Engineering (2004), 35B (5), 379-384CODEN: CPBEFF; ISSN:1359-8368. (Elsevier)
      Thermal cycling behavior of extruded aluminum-silicon alloy (Al-7% Si-0.7% Mg) based composites reinforced with 10 and 20 vol% particulate silicon carbide and the matrix alloy was studied. The composites and the matrix alloy were thermally cycled between 100 and 430° with the applied stresses below the yield strength, ranging from 3 to 15 MPa. The elongation to fracture and m' values were detd. Under certain loading and thermal cycling conditions, composite samples exhibit fairly high ductility, >80%, with an increase in m' value. The evaluation of the microstructures and RA values show that the thermally cycled samples contain cavities of varying amt. along the gauge and exhibit higher homogeneous plastic deformation than those isothermally tensile tested at 430°.
    58. 58
      Tjong, S. C.; Wang, G. S.; Mai, Y. W. Low-cycle fatigue behavior of Al-based composites containing in situ TiB2, Al2O3 and Al3Ti reinforcements. Mater. Sci. Eng.A 2003, 358, 99– 106,  DOI: 10.1016/S0921-5093(03)00266-1
      58
      Low-cycle fatigue behavior of Al-based composites containing in situ TiB2, Al2O3 and Al3Ti reinforcements
      Tjong, S. C.; Wang, G. S.; Mai, Y. W.
      Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing (2003), A358 (1-2), 99-106CODEN: MSAPE3; ISSN:0921-5093. (Elsevier Science B.V.)
      Aluminum-based composites reinforced with in situ TiB2 and Al2O3 particles were prepd. through reactive hot pressing of TiO2, Al and B powders. Brittle Al3Ti blocks were also formed in situ when the B/TiO2 mol. ratio is smaller than 2. The low-cycle fatigue behavior of in situ composites under total strain-controlled conditions at room temp. was investigated. The results showed that the composite reinforced with in situ TiB2 and Al2O3 particles exhibits a relatively stable cyclic response at low total strain amplitudes. At higher total strain amplitudes, cyclic softening from the onset of deformation was obsd. However, the presence of Al3Ti blocks led to a very slight cyclic hardening followed by softening at total strain amplitude of 0.4%. Moreover, the intermetallic Al3Ti blocks reduced the fatigue life of in situ composites as they promoted microscopic cracking during cyclic deformation. Finally, the fatigue life data of in situ composites can be described by the Coffin-Manson relationship.
    59. 59
      Llorca, J. An analysis of the influence of reinforcement fracture on the strength of discontinuously-reinforced metal-matrix composites. Acta Metall. Mater. 1995, 43, 181– 192,  DOI: 10.1016/0956-7151(95)90273-2
      59
      An analysis of the influence of reinforcement fracture on the strength of discontinuously reinforced metal-matrix composites
      Llorca, J.
      Acta Metallurgica et Materialia (1995), 43 (1), 181-92CODEN: AMATEB; ISSN:0956-7151. (Elsevier)
      A micromech. model was developed to study the influence of reinforcement fracture on the tensile strength of discontinuously reinforced metal-matrix composites. The analyses were carried out within the framework of the shear-lag model, which provides simple expressions for the av. stresses acting on the reinforcement as a function of matrix strength and reinforcement aspect ratio. The reinforcement strength was assumed to follow Weibull statistics, whereby the fraction of intact and broken reinforcements can be obtained for any combination of matrix and reinforcement properties. The overall composite strength was then calcd. by assuming that broken reinforcements do not contribute to strengthening of the composite. The model was used to study the influence of various parameters, such as matrix and reinforcement strength, and reinforcement aspect ratio and size. Finally, the model predictions were compared with exptl. results on several high-strength Al alloys reinforced by SiC particles.
    60. 60
      Kumai, S.; King, J. E.; Knott, J. F. Short and long fatigue crack growth in a SiC reinforced aluminium alloy. Fatigue Fract. Eng. Mater. Struct. 1990, 13, 511– 524,  DOI: 10.1111/j.1460-2695.1990.tb00621.x
      There is no corresponding record for this reference.
    61. 61
      Levy, G.; Linford, R. G.; Mitchell, L. A. Wear behaviour and mechanical properties: The similarity of seemingly unrelated approaches. Wear 1972, 21, 167– 177,  DOI: 10.1016/0043-1648(72)90255-4
      There is no corresponding record for this reference.
    62. 62
      Xue, Q. J.; Ludema, K. C. Plastic failure effects in scuffing of soft metals. Wear Mater. 1983, 499– 506
      There is no corresponding record for this reference.
    63. 63
      Ramesh, C. S.; Seshadri, S. K. Tribological characteristics of nickel based composite coatings. wear 2003, 255, 893– 902,  DOI: 10.1016/S0043-1648(03)00080-2
      63
      Tribological characteristics of nickel based composite coatings
      Ramesh, C. S.; Seshadri, S. K.
      Wear (2003), 255 (Pt. 2), 893-902CODEN: WEARAH; ISSN:0043-1648. (Elsevier Science B.V.)
      Nickel composite coatings were prepd. on mild steel substrates by sediment electro-co-deposition (SECD) technique. Silicon nitride, fly ash and calcium fluoride are used as the reinforcements. Metallog. studies, microhardness, friction and wear tests under various loads and sliding speeds were carried out on these coatings. Optical and SEM studies on the worn surfaces were conducted. A theor. model was used to predict the wear rates of the composite coatings. All the composite coatings exhibited a lower coeff. of friction and better wear resistance when compared with nickel coatings at all loads and sliding velocities studied. However, nickel-calcium fluoride composite coatings possessed the lowest coeff. of friction and wear rates. Significant effect of load and sliding speed on both the coeff. of friction and wear rates of nickel, nickel-silicon nitride and nickel-fly ash coatings was obsd. SEM studies of the worn surfaces reveal delamination process at higher loads. The predicted wear rates are in reasonable agreement with the exptl. values.
    64. 64
      Kumar, S.; Pandey, O. P. Role of fine size zircon sand ceramic particle on controlling the cell morphology of aluminum composite foams. J. Manuf. Process. 2015, 20, 172– 180,  DOI: 10.1016/j.jmapro.2015.08.006
      There is no corresponding record for this reference.
    65. 65
      Torrance, A. A. The effect of grit size and asperity blunting on abrasive wear. wear 2002, 253, 813– 819,  DOI: 10.1016/S0043-1648(02)00103-5
      65
      The effect of grit size and asperity blunting on abrasive wear
      Torrance, A. A.
      Wear (2002), 253 (7-8), 813-819CODEN: WEARAH; ISSN:0043-1648. (Elsevier Science B.V.)
      A model of abrasive wear, which has been used successfully to predict the forces and metal removal rates in abrasive machining is extended to allow the prediction of abrasive deterioration. Attritious wear of the abrasive and transfer of debris are both important factors in reducing abrasive wear over time, but small abrasives are more prone to becoming clogged by debris. Good quant. predictions of exptl. results are possible with the right input data, but much further work is needed to investigate the factors that are shown to control this process.
    66. 66
      Senthilkumar, M.; Saravanan, S. D.; Shankar, S. Dry sliding wear and friction behavior of aluminum–rice husk ash composite using Taguchi’s technique. J. Compos. Mater. 2015, 49, 2241– 2250,  DOI: 10.1177/0021998314545185
      There is no corresponding record for this reference.
    67. 67
      Gracia-Escosa, E.; García, I.; de Damborenea, J. J.; Conde, A. Friction and wear behaviour of tool steels sliding against 22MnB5 steel. J. Mater. Res. Technol. 2017, 6, 241– 250,  DOI: 10.1016/j.jmrt.2017.04.002
      67
      Friction and wear behaviour of tool steels sliding against 22MnB5 steel
      Gracia-Escosa, Elena; Garcia, Ignacio; Damborenea, Juan J. de; Conde, Ana
      Journal of Materials Research and Technology (2017), 6 (3), 241-250CODEN: JMRTAL; ISSN:2238-7854. (Elsevier B.V.)
      Boron steels are used in hot stamping process due to their good mech. properties. During the stamping process, the dies are exposed to aggressive conditions including adhesive wear, abrasion, thermal stresses and fatigue. In the present work, QRO 90 and UNIMAX slid against 22MnB5 steel in four conditions: with and without hardening treatment and, with and without Al-10%Si coating, in order to evaluate the influence of both coating and austenitization treatment on friction and wear of tool steels. The results showed that Al-10%Si reduces the friction coeff., while the hardening treatment results in an increase of COF due to Fe2Al5 brittle compds. Wear mechanism of both tool steels is adhesive and oxidative when tested against coated and uncoated 22MnB5, resp.
    68. 68
      Chaudhury, S. K.; Singh, A. K.; Sivaramakrishnan, C. S. S.; Panigrahi, S. C. Preparation and thermomechanical properties of stir cast Al-2Mg-11TiO 2 (rutile) composite. Bull. Mater. Sci. 2004, 27, 517– 521,  DOI: 10.1007/BF02707279
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      Preparation and thermomechanical properties of stir cast Al-2Mg-11TiO2 (rutile) composite
      Chaudhury, S. K.; Singh, A. K.; Sivaramakrishnan, C. S. S.; Panigrahi, S. C.
      Bulletin of Materials Science (2004), 27 (6), 517-521CODEN: BUMSDW; ISSN:0250-4707. (Indian Academy of Sciences)
      Al-2Mg-11TiO2 composite was successfully prepd. by the conventional vortex method. The macrostructural observation revealed columnar structure with rutile particles being distributed throughout the matrix in the form of agglomerates. Microstructural observation showed the presence of micro voids in the particle-enriched zone. Elec. resistivity measurement showed a phase transformation at 360°C, which was consistent during DSC studies due to the pptn. of TiAl3 phase. As-cast composite was both hot rolled and cold rolled successfully to 50 and 40% redn., resp. The mech. properties of the thermomechanically-worked composite were studied. From fractog. anal., it was clear that the crack had nucleated at the particle/matrix interface and propagated through the matrix by microvoid coalescence. Ultimate tensile strength of cold worked composite was found to be better than the hot worked material.
    69. 69
      Revankar, G. D.; Shetty, R.; Rao, S. S.; Gaitonde, V. N. Wear resistance enhancement of titanium alloy (Ti–6Al–4V) by by ball burnishing proceses. J. Mater. Res. Technol. 2017, 6, 13– 32,  DOI: 10.1016/j.jmrt.2016.03.007
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      Wear resistance enhancement of titanium alloy (Ti-6Al-4V) by ball burnishing process
      Revankar, Goutam Devaraya; Shetty, Raviraj; Rao, Shrikantha Srinivas; Gaitonde, Vinayak Neelakanth
      Journal of Materials Research and Technology (2017), 6 (1), 13-32CODEN: JMRTAL; ISSN:2238-7854. (Elsevier B.V.)
      The objective of the research was to improve the wear resistance of titanium alloys by ball burnishing process. Burnishing process parameters such as burnishing speed, burnishing feed, burnishing force and no. of pass were considered to minimize the specific wear rate and coeff. of friction. Taguchi optimization results revealed that burnishing force and no. of pass were the significant parameters for minimizing the specific wear rate, whereas the burnishing feed and speed play important roles in minimizing the coeff. of friction. After burnishing surface microhardness increased from 340 to 405 Hv, surface roughness decreased from 0.45 to 0.12 μm and compressive residual stress were generated immediately below the burnished surface. The optimization results showed that specific wear rate decreased by 52%, whereas coeff. of friction was reduced by 64% as compared to the turned surface. The results confirm that, an improvement in the wear resistance of Ti-6Al-4V alloy has been achieved by the process of ball burnishing.