Abstract Aluminum Matrix Composites Research Articles

Mechanical and tribological behaviour of novel Al–12Si-based hybrid composites

Abstract Aluminium matrix composites with high abrasion resistance, which can adapt to high temperatures and difficult operating conditions, are needed in the automotive and aerospace industries. For this purpose, Al–12Si–TiB2–Al2O3 composites were developed with the addition of TiB2–Al2O3 ceramic reinforcements at different rates and Gr at a constant rate. High densities were achieved by using the hot pressing method with powder metallurgy. Microstructural analyzes (SEM, EDS, X-RD) of the produced samples were made. In addition, mechanical properties (hardness and three-point bending) were investigated. The best tribological features were determined with the help of Taguchi, ANOVA and the prediction model. As a result, with the addition of TiB2 and Al2O3 reinforcements to the Al–12Si matrix, significant increases in hardness occur. In the bending analysis, it was determined that the reinforcements made the hybrid composite strong up to a certain point. From a tribological point of view, the A3 hybrid composite showed the best wear performance. Test conditions were analyzed with the help of Taguchi L18 orthogonal array and analysis of variance (ANOVA). With the help of ANOVA, it was determined that the most effective factors on the response parameters were the applied load and MMC type.

Effect of reinforcement particle amounts on dry sliding wear behavior of shot-peened SiC/A356 composites

Abstract Aluminum matrix composites focus primarily on improving mechanical properties such as hardness and wear, however, the softness of the aluminum matrix and thermal coefficient difference between matrix and reinforcement adversely affect these properties. In the present paper, the wear properties of aluminum matrix composites including different amounts of reinforcement were investigated before and after the shot peening process which was used for decreasing the harmful effects as mentioned. The experimental studies clearly reveal that shot peening, which is a mechanical surface treatment and generally used for improving fatigue resistance of materials, has a beneficial effect on the poor wear behavior of metal matrix composites. Obtaining results also indicate that the microhardness is improved greatly up to a certain depth by shot peening due to the higher dislocation density/microstrain which is evidenced with the X-ray diffraction tests.

Study on Mechanical Properties and Microstructure of FeCoCrNi/Al Composites via Cryorolling

Aluminum matrix composites (AMCs) reinforced by 1.5 and 3 wt% FeCoCrNi high-entropy alloy particles (HEAp) were obtained by a stir casting process. The AMCs strip was further prepared by room temperature rolling (RTR, 298 K) and cryorolling (CR, 77 K). The mechanical properties of the AMCs produced by RTR and CR were studied. The effect of a microstructure on mechanical properties of composites was analyzed by scanning electron microscopy (SEM). The results show that CR can greatly improve the mechanical properties of the HEAp/AMCs. Under 30% rolling reduction, the ultimate tensile strength (UTS) of the RTR 1.5 wt% HEAp/AMCs was 120.3 MPa, but it increased to 139.7 MPa in CR composites. Due to the volume shrinkage effect, the bonding ability of CR HEAp/AMCs reinforcement with Al matrix was stronger, exhibiting higher mechanical properties.

Joining of aluminium matrix composites using friction stir welding: A review

Aluminium matrix composites are one of the most important classes of materials and have become a major focus of attention in aerospace, aeronautical, defense, and automotive industries. Aluminium matrix composites when compared to conventional alloys offer various promising properties like excellent strength-to-weight ratio, higher stiffness, lower coefficient of thermal expansion, better dimensional stability, and tribological behavior. The properties of aluminium matrix composites are highly influenced by the appropriate selection of metal matrix, processing routes, and reinforcement. Various ceramic particles (oxides, carbides, nitrides, borides, etc.) are used as reinforcements for aluminium matrix composites. Significantly different properties may be obtained using various reinforced particles and matrix material, which makes it difficult for the traditional fusion welding techniques to meet the joining requirements of these composites and is restricted to certain grades of materials. Solid-state welding process offers greater advantages over the conventional fusion welding. As a solid-state joining process, friction stir welding has proven to be a better and promising technique for joining aluminium matrix composites. However, it is still subjected to various challenges to join aluminium matrix composites even with considerable progress has been made in recent years. The current review provides an overview of state-of-the-art of friction stir welding of aluminium matrix composite materials. Specific attention and critical assessment have been given to weldability, the macrostructure and microstructure of aluminium matrix composite joints, mechanical properties of joints, fractography, and the wear of friction stir welding tool during welding of aluminium matrix composite. Furthermore, the various existing challenges of friction stir welding of aluminium matrix composites are summarized and the recommendations for future research are proposed.

Effect of the Hot Deformation Conditions on Structure and Mechanical Properties of AlCr/AlCrSi Powder Composites

Aluminum matrix composites usually contain strengthening particles of refractory compounds (SiC, Al2O3) that do not react with the Al matrix. There is a problem in producing the Al matrix composite with inclusion of metals that can generate intermetallic compounds with aluminum. In this case, a conventional sintering of powder mixtures results in high porosity due to volume growth. That is why some new methods of producing dense Al matrix composites are required. A possibility to create a dense powder Al-based composite containing hard components, such as chromium and silicon, without using the sintering process, is considered. This paper presents study results of structural and mechanical properties of Al-Cr and Al-Cr-Si composites produced by hot compaction of powder mixtures. An analysis of the relationship between mechanical properties and structures of Al-Cr and Al-Cr-Si composites is carried out. Optimal values for thermomechanical processing modes that ensure sufficient strength and plasticity are determined. It is shown that strong bonding of the aluminum particles occurs under hot deformation, and an aluminum matrix is formed that provides acceptable composite bending strength as a result. The presence of chromium and silicon hard inclusions is not a significant obstacle for aluminum plastic flow. Al-Cr and Al-Cr-Si composites produced by hot deformation of the powder mixtures can be used as cathode material for the deposition of wear-resistant nitride coatings on metalworking tools.

Milling of an Aluminium Matrix Composite Using MCD-Tipped Tools with Adjusted Corner and Minor Cutting Edge Geometries

Aluminium matrix composites (AMCs) represent suitable materials for lightweight design applications. The abrasive ceramic reinforcements typically require diamond cutting materials to prevent excessive tool wear. In milling with diamond cutting materials the influence of cutting parameters was already examined to a significant extent. Investigations concerning the effect of modified tool geometries are limited and the potentials with regard to the geometrical and physical surface properties are unclear. Accordingly, experimental investigations in milling of a 10 vol.% SiC particle-reinforced aluminium wrought alloy EN AW-2017 T4 were addressed. The effect of modified corner and minor cutting edge geometries were investigated based on mono crystalline diamond (MCD)-tipped tools to benefit stable process conditions. The results indicated achievable areal roughness values in the range around 0.2μm. Especially the application of the lowest cutting edge angle and a trailing minor cutting edge led to strong fluctuations of the surface parameters. The lowest valley void volumes were achieved with an arched minor cutting edge. Generally, finish machining led to stronger compressive residual stresses compared to the state prior to machining. The strongest increase was achieved using a corner radius combined with a straight minor cutting edge. It is concluded that reduced effective radii generating the surface enable an acceptable surface structure and strong compressive residual stresses and should be addressed in further investigations.

Studies on corrosion behaviour of sintered aluminium based composites in chloride environment

Aluminium matrix composites have been developed to replace other conventional engineering materials in specific industries where enhanced properties are required. The corrosion susceptibility of sintered unreinforced aluminium and composites in chloride medium (AMCs) were studied. The powders of pure as-received aluminium (matrix) and particles of ferrotitanium and silicon carbide particles were homogeneously dispersed using ball milling technique. Powder metallurgy route was utilised for consolidating the milled powders into a sintered compact. Microstructural examination of the compacted pure aluminium and composites confirmed an even distribution of the reinforcements in the aluminium matrix. The produced composites also recorded an improved corrosion resistance in a corrosive medium of 3.5 wt.% laboratory prepared sodium chloride, from the potentiodynamic polarization and chronoamperometry (potentiostatic) tests. The corroded specimens were further assessed for pitting using a field emission scanning electron microscope (FE-SEM). The resistance of the fabricated samples to corrosion was improved upon the addition of TiFe and SiC reinforcements.

The role of ceramic particle loading and the influence of hot extrusion on the tribological behaviour of aluminium alloy-SiCp composites

Aluminium matrix composites (AMC) are gaining wide popularity in various sectors due to their excellent properties which are synergic. Apart from strength, wear resistance of a material is also an essential criterion for the number of applications. Extensive studies are being carried out on the secondary processing of these materials to enhance the suitability of the AMC for engineering applications. In this study, initially, Al 2014 base alloy and their composites with 5, 10, and 15 wt.% SiCp fabricated by stir casting route were subjected to wear test. Based on the encouraging wear performance, the Al-10 wt.% SiC composite was further subjected to extrusion. Pin-on-disc sliding wear tests on the as-cast & extruded base alloy and the composite samples were carried out at a constant load of 20 N for a total sliding distance of 1000 m with a velocity of 2 m/s. Microhardness and porosity measurements were carried out besides the study of wear performance, such as coefficient of friction and wear by weight loss. The worn surfaces were analyzed both by optical and scanning electron microscopes. The effect of particle addition, extrusion, porosity, and microhardness on the wear performance of the samples was discussed. Among the samples studied, the Al-10 wt.% SiC composite extruded at a ratio of 8:1 is found to have the highest wear resistance.

New Emerging Al7075 Based Hybrid Nanocomposite for Automotive Applications: A Sustainability Approach

Aluminium matrix composites (AMCs) have emerged as the substitute for the monolithic (unreinforced) materials over the past few decades. The applications of AMCs are common in automotive, aerospace, defence and biomedical sectors due to its lower weight, high strength, high resistance against corrosion and high thermal and electrical conductivity. In this work, it is aimed fabricate a new class Al 7075 based hybrid composites reinforcing with nanoparticulates suitable for automotive application. Al7075 reinforced with fixed quantity of boron carbide (B4C) (1.5 wt.%) and varying wt % of flyash (0.5 wt.%, 1.0 wt.%, 1.5 wt.%) is fabricated using ultrasonic-assisted stir casting technique. Physical and mechanical characterization such as density, porosity, micro hardness, tensile strength and impact strength were estimated for three different compositions. The tensile strength and percentage increase in hardness value of the nanocomposite Al7075-B4C (1.5 wt. %)-flyash (0.5 wt. %): HNC3 found maximum as 294 MPa and 32.93%. In comparison with Al7075 alloy the impact strength of HNC3 shows the highest percentage of 9.31% respectively.

Effect of Nano-Al<sub>2</sub>O<sub>3</sub> on Characteristics of Aluminium A356 Matrix Composite Produced by Stir Casting Route

Aluminium Matrix Composites (AMCs) made by A356 as matrix and nanoAl2O3 as reinforced are widely used for high performance application because of light weight and alumina has good performance at high temperature. In this study, the nanoAl2O3 used varied from 0.1 vf-% to 1.2 vf-%, which subsequently determined the optimum point. In addition, the magnesium with 10% are added as a wetting agent between aluminium and nanoAl2O3 as reinforced. Stir casting process is carried out for 2 minutes and 4 minutes for the degassing process using argon gasses then pouring molten metal in to the mold at 800°C. The effect of nanoAl2O3 on the mechanical properties and microstructure of the composites was investigated. The result showed that the tensile strength decreased with the addition of nanoAl2O3 but the hardness increased. Increasing of hardness mainly caused by grain refinement, and particle strengthening which act as obstacles to the motion of dislocations. Addition of nanoAl2O3 as reinforced also tend to form microporosity and agglomeration which would decrease the tensile strength of composites. The optimum strength was reached by 0.5 %Vf nanoAl2O3 with the value of 140 MPa and hardness of 46 BHN which was supported by low porosity level. Keyword : Al A356, Al2O3, nanoComposite, Stir Casting

Electrical conductivity, magnetic and fatigue properties of aluminum matrix composites reinforced with nano-titanium dioxide (TiO2)

Aluminum matrix composites are widely used in many structural application due to properties like high specific strength, wear resistance, lightweight and fatigue properties. The aim of the current work is to investigate the effect of the addition of nanosize participles to AA6063-T4 aluminum alloy on the electrical conductivity, magnetic and fatigue properties of composites produced by stir casting method. It was revealed that the AA6063-T4/ composites were successfully prepared with 3 wt%, 5 wt% and 7 wt% TiO2 using a stir casting technique with electrical conductivity increasing with increasing amount of Also it was found that the electrical conductivity of all composites was higher than the base metal matrix and the conductivity was proportion to the frequency for both matrix and composites. The magnetic studies revealed an improvement of the nanocomposites in comparison with the base metal. The fatigue life and fatigue strength of 7 wt% TiO2 composite was found to be higher than that of other composites and base matrix.

Physical and Mechanical Properties of Graphene Nanoplatelet-Reinforced Al6061-T6 Composites Processed by Spark Plasma Sintering

Aluminium matrix composites with high specific strength are attracting attention for use in automobile and aerospace applications. Graphene nanoplatelets (GNPs) were added in 0.1, 0.5, and 1 weight fractions to an Al6061 matrix. Spark plasma sintering was used with a combination of solution sonication and ball milling to disperse the GNPs in the Al6061 matrix. The evolution of the microstructure was studied using optical and scanning electron microscopy. The uniformity of the GNP distribution is discussed in light of selected ball milling parameters. Electron backscattered diffraction analysis was used to measure the grain size and misorientation. X-ray diffraction analysis and transmission electron microscopy revealed neat and clean interfaces between the matrix and GNPs. Hardness and tensile testing revealed a considerable increment in the strength of the final composite after addition of GNPs. Traces of GNP clusters were found in the 1 wt.% composite as well as premature failure at lower strain due to the insufficient load transfer capability of the Al6061-T6 matrix. An illustrative two-dimensional model was developed to explain the load transfer behavior and the deterioration of the mechanical properties.

EFFECT OF Al2O3 COATED Cu NANOPARTICLES ON PROPERTIES OF Al / Al2O3 COMPOSITES

Aluminum matrix composites reinforced with various contents of Al2O3 nanoparticles coated with Cu (0, 5, 10 and 15 wt. %) were prepared by powder metallurgy technique. Al2O3 particles are coated with 30 wt. % Cu by electroless deposition after surface activation using 10 wt. % silver. Appropriate amounts of Al and Al2O3 (coated with Cu) are well mixed in a ball mill (4:1 balls to powder ratio) for 6 h. Then, the mixture is sintered by hot pressing at 500oC under 700 MPa uniaxial pressure for 45min in argon atmosphere. Phase identification and microstructure of sintered samples are studied. The density, thermal expansion and mechanical properties were measured. Increasing Al2O3 nanoparticles coated with Cu highly influences composite samples. Good distribution of Al2O3 coated with Cu in the Al matrix and their improved wettability, improve the microstructure, hardness, compressive strength and thermal expansion properties. However, addition of Al2O3 coated with Cu shows a deteriorated effect on both densification and ductility.

Fatigue and Compression Characteristics of Al 6061–B4c Composite Materials

Aluminum matrix composites reinforced with boron carbide are a kind of materials that are widely used because of high strength, low density, and improved tribological properties. In this study, mechanical properties of Al 6061–B4C composites reinforced with B4C of three different particle sizes were investigated. In the Al 6061–B4C composite materials, produced by the powder metallurgy methods (extrusion of billets obtained by sintering at temperature of 550°C under pressure of 450 MPa), the change of mechanical properties such as hardness, compressive strength, and fatigue life, related to B4C particle size and the applied heat treatment mode (aging at 180°C for 5 h), were investigated. The hardness of the materials is increased with B4C grain size and the heat treatment. After the heat treatment, the fatigue life of Al 6061–B4C (3 μm) material increases slightly, while that of the composite materials decreases with larger size of B4C reinforcement. The fatigue life of the composite materials reinforced with a larger grain size B4C is reduced by heat treatment. While the compression test data of untreated composite materials were similar to each other, the heat treatment increased these values in all samples. The highest increase in the compression strength was observed in the composite reinforced with 17 μm sized B4C. The addition of graphite reduces the deformation ability of the composites.

Experimental Investigations on Vibration Properties of Aluminium Matrix Composites Reinforced with Iron Oxide Particles

Aluminium matrix composites offer improved damping properties than other metals and its alloy. Generally pure metals and its alloys may have fairly good mechanical properties but falls short in damping properties. Aluminium matrix composites are becoming important in aerospace automobile and marine applications due to its god damping properties. The present investigation is concerned with the damping capacity of iron oxide (Fe2O3) reinforced aluminium matrix composite. The composites were fabricated with 2%, 4% and 6%, by weight of iron oxide with varied particle of size 40 μm and 500 nm in equal proportions using stir casting process. From the results obtained the 500 nm size with 4 wt% of iron oxide showed improved dynamic properties. The iron oxides reinforced with aluminum matrix are found to be new substitutes for the existing materials with low damping properties.

Tribological Analysis by Concentration Effect of Boron Carbide and Graphite on the Aluminum Composites

Aluminium matrix composites (AMCs) are indispensable materials used extensively in the aerospace and automobile industries and are highly endorsed due to their good mechanical properties. In this paper, various compositions of the AMCs were fabricated, tested and analyzed using pin on disc tribometer test to understand the tribological behaviour and wear mechanism properties. The volume percentages of the Aluminium composite reinforced with boron carbide and graphite present in the form of Al-B4C-Graphite are Al-B4C (5%)-Graphite (5%), Al-B4C (10%)-Graphite (5%), Al-B4C (5%)-Graphite (15%), Al-B4C (10%)-Graphite (15%), Al-B4C (15%)-Graphite (15%). Loads were varied in steps of 10N, from 10N to 50N while the sliding velocity was correspondingly set as 0.7, 1.4 and 2.1m/s. SEM image analysis was conducted to understand surface tribology after wear tests. The composite Al-B4C (15%)-Graphite (15%) exhibited best wear resistance which can be credited to the bearing capacity of boron carbide particles and adherent graphite layer.

Wear Rate and Thermal Conductivity of a Copper-Plated Graphite Flake/Aluminum Composite

Aluminum matrix composites with nondirectional graphite-flake reinforcement were fabricated by hot-press sintering. To avoid interfacial reactions in the graphite-flake-reinforced composites, copper (Cu), with a thickness of approximately 50 μm, was coated on the graphite flakes by chemical plating. The results show that the Cu is uniformly distributed on the surface of graphite flakes. The thickness of the Cu plating is in the range of 15.3–21.2 μm. For volume fractions of the nondirectional graphite flakes ranging from 40% to 70%, the Al/Cu-plated graphite-flake (Cu-GF) composites display thermal conductivities from 328 W/m K to 612 W/m K. The theoretical values calculated by the parallel alternate layer model are slightly higher than the experimental values. The friction coefficient (0.171) and wear rate (2.31 × 10−7 mm3/N mm) of the composites with 70% Cu-plated graphite flakes are the lowest of the compositions observed in this study. Owing to the lubrication of graphite, the friction coefficient and wear rate decrease with increasing graphite flake content. The thermal conductivity and wear resistance gradually increase when the volume fraction of the Cu-plated graphite flake increase.

Effect of red mud and TiC on friction and wear characteristics of Al 7075 metal matrix composites

ABSTRACT Aluminum matrix composites are preferred in various engineering fields such as automobile, marine and aerospace applications owing to their superior properties like high strength to weight ratio, and good wear resistance. The main challenge is to produce MMCs with high strength and wear resistance in a cost-effective manner by utilizing the industrial waste known as red mud is used as reinforcement. In the present study, Al7075/TiC and Al7075/red mud composite samples are fabricated separately after using liquid metallurgy route. During fabrication, the preheated (200-250°C) red mud and TiC reinforcement particles are added at different levels in the ranges from 3–12 wt % in steps of 3 wt% of aluminum. Dry sliding wear and friction characteristics of the fabricated MMCs are studied on a pin on disc wear and friction monitor with and without heat treatment condition. The results have shown improvement for both the specific strength and wear resistance of the developed samples when matched with the base alloy. Further, it is also witnessed that the Al7075/TiC has shown 8 and 19 percentage of improvement in the coefficient of friction and wear rate, respectively when compared with Al7075/red mud composite. Abbreviation: MMCs: Metal Matrix Composites; TiC: Titanium Carbide; SEM: Scanning Electron Microscope; XRD: X-Ray Diffraction

Microstructural And Corrosion Resistance Study Of Sintered Al-Tin In Sodium Chloride Solution

Abstract Aluminium matrix composites were produced by adding 2, 4, 6 and 8 wt. % of titanium nitride (TiN) nanoparticles respectively to aluminium matrix through powder metallurgy technique. The mixed powder was compacted at a pressure of 50 MPa to produce the specimens. The specimens were sintered in nitrogen atmosphere at a sintering temperature of 400°C with sintering time of 2 hours for each. Microstructural and mechanical properties of sintered composites was investigated. Potentiodynamic polarization test was conducted to determine the corrosion behaviour of sintered samples in sodium chloride.

Microstructure and mechanical properties of SiCp/ZL105 composite prepared by electromagnetic stirring

Aluminum matrix composites reinforced with SiC particles (SiCp) were prepared by electromagnetic stirring. This article aims to study the effects of SiCp addition on microstructure and mechanical properties of SiCp/ZL105, finally leading to expended range for ZL105 alloy application. Microstructural studies were carried out by optical microscope, scanning electron microscopy, and energy dispersive spectrometer. Tensile and hardness tests were conducted in order to identify mechanical properties. It was found that addition of 1.5 wt% SiCp causes the refined microstructure (including primary α-Al and eutectic Si) and reduced secondary dendrite arm spacing of α-Al matrix (12.6 μm). Compared to the ZL105 alloy, the ultimate tensile strength, elongation, and hardness of the composite with 1.5 wt% SiCp were increased by 24.6%, 37.3%, and 27.0%, respectively. The improved mechanical properties can mainly be attributed to the refinement of primary α-Al and eutectic Si, and uniformed dispersion of SiCp. Furthermore, the effects of voltage and agitation frequency of magnetic field on microstructure of composites were discussed.