Al Alloy Matrix Composites Research Articles

Effect of Cu alloying on the damping and compression properties of graphene nanoplatelets reinforced Al-30Zn-xCu alloy matrix composites

For a long time, metal matrix composites (MMCs) have always faced a trade-off between damping and mechanical properties, and this is especially true for high-Zn Al alloy matrix composites. In this study, graphene nanoplatelets (GNPs) reinforced Al-30Zn-xCu-0.5GNPs laminated composites with excellent damping-mechanical property balance were fabricated by flake powder metallurgy and Cu alloying. The addition of Cu element greatly refines the intragranular and intergranular precipitated η-Zn phases, which not only increases the Al-Zn interfacial area but also weakens the tendency of cracking at the grain boundaries. The increased Al-Zn interfacial area is conducive to the improvement of the damping performance of the composites through the interfacial damping mechanism, but the excessive generation of θ-CuAl2 induced by too high Cu additions will harden the matrix, resulting in a simultaneous decrease in the damping performance and plasticity.

Unveiling the strengthening and toughening effects of copper-coated carbon nanotubes for the AlLiCu alloy matrix composite

Carbon nanotubes (CNTs) reinforced Al–Li–Cu alloy matrix composite is a promising candidate for the lightweight structural materials demanded in advanced industrial areas such as aerospace. However, how to fully exploit the combined strengthening effects of CNTs and precipitates of the Al–Li–Cu matrix is still an open issue. In the present study, the Cu coating was firstly precoated on CNTs before fabricating CNTs reinforced Al–Li–Cu alloy matrix composite. Benefiting from the Cu coating, the improved CNTs dispersion and Al-CNTs interfacial bonding was achieved, and the precipitation of Al2Cu, Al2CuLi, and Al3Li was enhanced in the AlLiCu alloy matrix, resulting in the enhanced strength-ductility synergy for Cu-coated CNTs reinforced AlLiCu alloy matrix composite. Moreover, strengthening and toughening mechanisms analyzation reveals that the Orowan strengthening of CNTs and precipitates, as well as load transfer strengthening of CNTs contribute mostly to the improved strength, while the increased ductility dominantly derives from the improved CNTs dispersion and Al-CNTs interfacial bonding, and the formation of low-density dislocation nanoregion (LDDN) in the interface area. This study not only opens up a new way for developing the AlLiCu alloy matrix composite reinforced by Cu-coated CNTs but also guides the microstructure regulation of other Al alloy matrix composites.

Characterization of wear rate of Al-12 wt%Si alloy based MMC reinforced with ZrO2 particulates

The primary objective of this study is to fabricate an Al-12 wt% Si Alloy/ZrO2 composite using the Stir Casting technique, with a specific focus on assessing its performance, particularly in terms of wear characteristics. This research presents a unique approach by utilizing Al-12 wt% Si Alloy as the matrix material, aiming to develop tailored Al Alloy matrix composites suitable for applications requiring enhanced tribological properties. The composites are systematically manufactured with varying percentages of micro-sized ZrO2 reinforcements, specifically 0.5, 1, and 3 wt%. The incorporation of ZrO2 results in significant improvements in wear resistance, a critical attribute for Al-12 wt% Si Alloy-based composites. These composites find extensive utility across industries such as marine, aerospace, automotive, and the power sector, where they are indispensable for producing vital components like electrical sliding contacts, gears, bearings, bushes, pistons, piston rings, and clutches. Despite the availability of various promising reinforcement materials, researchers persistently explore novel combinations of matrices and reinforcements to tailor properties and enhance cost-effectiveness. ZrO2 has emerged as a notable reinforcement material in metal matrix composites, as evidenced by numerous research endeavours. The composites fabricated with ceramic reinforcement’s exhibit enhanced tribological characteristics. The study observes that the wear rate decreases up to 3 wt% of reinforcements, beyond which it increases due to reinforcement agglomeration. The optimal wear-resistant combination is found at 3 wt% of ZrO2, attributed to robust micro-coring and interstitial metal-oxygen bonding facilitated by the Si content in the Al-12%Si matrix. The results are further optimized using Response Surface Methodology (RSM) techniques and validated using the ANOVA table to elucidate the behaviour of the composites under different operational conditions. The hardness results further ascertain the decrease in the wear rate due to the inclusion of ZrO2 reinforcements owing to micro coring and strengthening.

Fatigue crack growth rate and propagation mechanisms of SiC particle reinforced Al alloy matrix composites

PurposeThis study aims to investigate the fatigue crack propagation behavior of SiC particle-reinforced 2124 Al alloy composites under constant amplitude axial loading at a stress ratio of R = 0.1. For this purpose, it is performed experiments and comparatively analyze the results by producing 5, 10, 15 Vol.% SiCp-reinforced composites and unreinforced 2124 Al alloy billets with powder metallurgy (PM) production technique.Design/methodology/approachWith the PM production technique, SiCp-reinforced composite and unreinforced 2124 Al alloy billets were produced at 5%, 10%, 15% volume ratios. After the produced billets were extruded and 5 mm thick plates were formed, tensile and fatigue crack propagation compact tensile (CT) samples were prepared. Optical microscope examinations were carried out to determine the microstructural properties of billet and samples. To determine the SiC particle–matrix interactions due to the composite microstructure, unlike the Al alloy, which affects the crack initiation life and crack propagation rate, detailed scanning electron microscopy (SEM) studies have been carried out.FindingsOptical microscope examinations for the determination of the microstructural properties of billet and samples showed that although SiC particles were rarely clustered in the Al alloy matrix, they were generally homogeneously dispersed. Fatigue crack propagation rates were determined experimentally. While the highest crack initiation resistance was achieved at 5% SiC volume ratio, the slowest crack propagation rate in the stable crack propagation region was found in the unreinforced 2124 Al alloy. At volume ratios greater than 5%, the number of crack initiation cycles decreases and the propagation rate increases.Originality/valueAs a requirement of damage tolerance design, the fatigue crack propagation rate and fatigue behavior of materials to be used in high-tech vehicles such as aircraft structural parts should be well characterized. Therefore, safer use of these materials in critical structural parts becomes widespread. In this study, besides measuring fatigue crack propagation rates, the mechanisms causing crack acceleration or deceleration were determined by applying detailed SEM examinations.

Stacking faults in a mechanically strong Al(Mg)–Al3Mg2 composite

Stacking faults (SFs), similar to other planar defects such as grain boundaries, twin boundaries and heterogeneous interfaces, can be tailored to simultaneously increase strength and ductility of metal matrix composites. However, SFs are rarely observed in Al alloy matrix composites, resulting from the high stacking fault energy (SFE) (166 mJ/m2) of pure Al and its weak dependence on most alloying elements. Therefore, strengthening Al alloy matrix composites with SFs has been a longstanding challenge. In the current work, SFs with a density of 2.8 × 1015 m−2 are introduced into an ultrafine-grained Al(Mg)–Al3Mg2 composite fabricated by extruding compacted mechanically alloyed and nanostructured Al-11 at.% Mg alloy powder at 703 K. These SFs, together with grain boundaries and solute Mg, increase the yield strength of the as-extruded composite to 700 MPa at a tensile elongation of ∼4%. We show that the Al(Mg) alloy matrix-Al3Mg2 interfaces enable the formation of the densely arranged SFs. This finding offers a pathway to tailoring high strength Al alloy matrix composites through manipulating SFs by interface engineering.

Optimization of dry sliding wear behavior of Si3N4 and Gr reinforced Al–Zn–Mg–Cu composites using taguchi method

The sliding wear behavior of stir cast silicon nitride (Si3N4) and graphite (Gr) reinforced Al–Zn–Cu–Mg (Al alloy) matrix composites were investigated under dry conditions. Al alloy/1 wt.% Si3N4 composite, Al alloy/1 wt.% Si3N4–xGr hybrid composites (x = 1.5 and 3% Gr by weight) were separately developed to examine their wear behavior. Microstructure and EDS characterization were used to identify the reinforcement (Si3N4 and Gr) in casted composites. Experimental design with L–27 orthogonal matrix array was chosen to perform the wear experiments to examine the effect of various applied normal loads (15 N, 30 N, and 45 N) and sliding velocities (0.523, 1.047, and 1.57 m/s) at a constant sliding distance of 1000 m. Results reveal that the wear rate significantly decreased after adding 1.5 and 3 wt.% Gr in Al– Si3N4 composite and obtained a minimum wear rate for hybrid composites containing 3 wt.% Gr particles. ANOVA results revealed that load is the most dominating factor in wear rate, followed by sliding velocity and Gr content. The worn surface study observed lesser micro-cracks and pits in the hybrid composite containing 3 wt.% Gr compared to Al– Si3N4 composites. The uniform distribution of reinforcing particles in the Al alloy matrix was examined through SEM characterization of casted samples.

Manufacturing and Performance of Carbon Short Fiber Reinforced Composite Using Various Aluminum Matrix

A new fabrication process without preform manufacturing has been developed for carbon short fiber (CSF) reinforced various aluminum matrix composites. And their mechanical and thermal properties were evaluated. Electroless Ni plating was conducted on the CSF for improving wettability between the carbon fiber (CF) and aluminum. It was confirmed that pores in Ni plated CSF/Al and Al alloy matrix composites prepared by applied pressure, 0.8 MPa, had some imperfect infiltration regions between the CF/CF and CF/matrix in all composites. However, pores size in the region between the CF/CF and CF/matrix to use the A336 matrix was about 1 µm. This size is smaller than that of other aluminum-based composites. Vickers hardness of Ni plated CSF/A1070, A356 alloy, and A336 alloy composites were higher as compared to matrix. However, the A1070 pure aluminum matrix composite had the highest hardness improvement. The Ultimate tensile strength of the A1070 and A356 aluminum matrix composite was increased due to carbon fiber compared to only aluminum, but the Ultimate tensile strength of the A336 aluminum matrix composite was rather lowered due to the highest content of Si precipitate and large size of Al3Ni compounds. The Thermal Conductivity of Ni plated CSF/A1070 composite has the highest value (167.1 W·m−1·K−1) as compared to composites.

Comparison of tool wear during friction stir welding of Al alloy and Al-SiC metal matrix composite

Aluminum matrix composites have received considerable attention due to their high specific strength and specific stiffness, high hardness, and wear resistance along with being light in weight. These composites are preferably joined using friction stir welding process. The major concern in friction stir welding is the wear of the welding tool pin which is the backbone of the process. The wear is due to the prolonged contact between the tool and the harder reinforcements in the composite materials. The present work deals with the study of tool wear and its surface roughness with respect to different selected friction stir welding parameters such as rotational speed, transverse speed, length of weld, and different composition of Aluminum composite. It was found that the total amount of material removed from the tool and the surface roughness of the tool is in direct proportion to the rotational speed of the tool and the length of the weld but inversely proportional to the transverse rate. The increase in wt.% of SiC reinforcement leads to the higher tool wear but reduces the surface roughness of the tool.

Comportamiento del flujo de esfuerzo y análisis microestructural de compuestos de matriz de aluminio deformados en caliente y reforzados con partículas de la aleación con memoria de forma CuZnAlNi

Se investigó el comportamiento del flujo de esfuerzo por compresión y las microestructuras de los compuestos de matriz de aleación de Al deformada en caliente (AMC) y reforzados con partículas de la aleación con memoria de forma (SMA) basadas en CuZnAlNi. La aleación base Al-Mg-Si reforzada con 4, 6 y 8% en peso de Cu-18Zn-7Al-0,3Ni, y 8% en peso de partículas de SiC, se obtuvieron mediante agitación doble y se sometieron a pruebas de compresión en caliente a una velocidad de deformación de 1,0 s−1, temperatura de 400 °C, y ~60% de defor­mación global constante, para ello se utilizó un simulador termo-mecánico Gleeble 3500. Las microestructuras iniciales y deformadas de los compuestos se examinaron utilizando microscopía óptica. El uso de partículas Cu-18Zn-7Al-0,3Ni como refuerzo dio como resultado el desarrollo de una estructura de matriz más fina en comparación con el SiC. La tensión de flujo y la dureza de los AMC reforzados con partículas de Cu-18Zn-7Al-0,3Ni fueron generalmente más altos que los de la aleación de Al no reforzada y la aleación de Al reforzada con SiC. También la tensión de flujo y, en gran medida, la dureza creció con el aumento en el porcentaje en peso de partículas de Cu-18Zn-7Al-0,3Ni en el AMC. La mejora observada con el uso de partículas de la aleación Cu-18Zn-7Al-0,3Ni se atribuyó a la combinación del refuerzo mejorado y el refinamiento del tamaño grano de la matriz, fortalecimiento la interface, el esfuerzo residual de compresión, la alta conductividad térmica, y la capacidad de amortiguación ofrecida por la aleación Cu-18Zn-7Al-0,3Ni.

Microstructural characterization and evaluation of mechanical properties of silicon nitride reinforced LM 25 composite

This study focuses on the effect of the reinforcement of Si3N4 particles on the microstructure, and mechanical properties of LM25 Al alloy matrix composites fabricated by the stir casting process. The reinforcement content was varied from 4% to 12% in steps of 4%, for a set of three composites. The microstructures and morphology of the developed composites were studied by SEM and EDS. The amount of different elements present in the reinforcement, matrix and the three sets of composites is demonstrated using elemental mapping. The result of this investigation revealed that a uniform distribution of Si3N4 particles takes place at all weight percentages of reinforcement in LM 25 alloy, with limited non-uniformity due to clustering of ceramic particles. The mechanical properties were also evaluated and analysed for the fabricated AMCs. A fracture surface mapping was also carried out for the composites.

Evaluation of Microstructural Characteristics of High-Si Al Alloy Cylindrical Samples Produced by Rheological Squeeze Casting with Bottom-Up Filling and Flow State Analysis of the Alloy Semi-Solid Slurries

The microstructures of high-Si Al alloy cylindrical simples produced by rheological squeeze-casting with bottom-up filling were investigated. The effect of process parameters on the distribution of hard phases (primary Si and Fe-rich phase) was evaluated, and flow characteristics of semi-solid slurry of high-Si Al alloy were investigated. Differences in volume fractions (VFs) of hard phases between the middle and upper layers of cylindrical samples decreased as the squeezing speed increased. Moreover, the flow state of the semi-solid alloy slurry transitioned from laminar to turbulent flow as the squeezing speed was increased. Movement of gases throughout the semi-solid alloy slurry filling process was analysed under different process parameters. The results provide insights for improving rheological casting of high-Si Al alloy and other Al matrix composites.

Evaluation of tribological behaviour of AA7178/Gr composites using Taguchi optimization technique

Graphite is a broadly utilized incorporating content to augment the tribological characteristics of the aluminium alloy based composites (AMCs). Al alloy (AA7178) matrix composite was created with various proportionate of graphite (Gr) content via stir casting process. L16 orthogonal array was utilized to conduct the wear test in Pin-on disk device. The values of the experiments are in accordance with the Taguchi approach. The dry sliding wear aspects were optimized by Signal/Noise ratio and Analysis of Variance (ANOVA) analysis. The foremost essential aspects are applied load, which has the uppermost contribution of 50%, followed by a sliding distance factor with a 17.5% contribution, a volume concentration factor with a 5% contribution, and a sliding speed aspect with a contribution of 2.5% on composite specimens. ANOVA analysis outcome exhibits that, the weight proportionate of incorporating content has the superior proportionate of contribution to impact the wear rate of the AMCs.

Atomic-scale investigation of the interface precipitation in a TiB2 nanoparticles reinforced Al–Zn–Mg–Cu matrix composite

The effects of nanosized reinforcement particles on precipitation reactions in age-hardenable Al alloy matrix composites have been largely unknown. In this work, an Al–Zn–Mg–Cu matrix composite reinforced with uniformly distributed TiB2 nanoparticles was successfully produced. The solid-soluted, peak-aged and overaged materials were then characterized, at the atomic scale using (high-resolution) scanning transmission electron microscopy, to provide a fundamental insight into the interface precipitation. Our results demonstrated that the facetted TiB2 nanoparticles have a significant impact on the precipitation in matrix areas adjacent to the TiB2/Al interfaces. The interfaces after solid-solution treatment are tightly-bonded and oxide-free. The TiB2 particles and Al matrix display two orientation relationships (ORs): the well-reported [21¯1¯0]TiB2//[101]Al, (0001)TiB2//(1¯11)Al (OR1) and the new [21¯1¯0]TiB2//[101]Al, (011¯0)TiB2//(111¯)Al (OR2). The interface precipitates (i.e., interphase) having the size of several tens of nanometers were formed after ageing and were determined to be (Zn1.5Cu0.5)Mg phase. Their formations were only related to the initial OR1 and OR2 where the mutual ORs between the TiB2, interphase and Al matrix were further developed. Periodically spaced misfit dislocations were revealed at the semi-coherent TiB2/Al interfaces, which are generally considered beneficial to the heterogeneous precipitation. They not only reduced nucleation energy barrier, but also acted as short-circuit diffusion paths for transporting solute atoms and vacancies, accelerating growth rate. However, the growth of interphase at the interface parallel to close-packed {111} Al planes was suppressed by the ultra-low accommodation factor. In addition, such an interface precipitation reduced the mismatch of the TiB2/Al interface, increasing the overall coherency and being potential for effective interface strengthening.

Gravel powder effect in reinforced aluminum alloy matrix composite

Abstract In the present study, the effect of gravel powder content on both mechanical and wear properties of Al alloy matrix composite were investigated. Aluminum with 4 vol% copper particles were used as the matrix and reinforced by 0, 4, 8, 12, and 16 vol% gravel powder. Powder metallurgy route is used to manufacture the composites. The composite samples were characterized by utilizing a Scanning Electron Microscope (SEM), Energy-Dispersive X-ray (EDX) analyses, and elemental mapping analysis. The wear test was obtained under the different time of 10, 20, and 30 min at a constant load of 20 N. The results showed that the composites density decreases, and the porosity increases with improving in gravel powder content. Furthermore, it was found improving in hardness, diametral compressive strength, and wear resistance by enhancement in gravel powder content. Whereas increasing in wear time results deterioration in wear resistance.

Microstructure and mechanical property of bimodal-size metallic glass particle-reinforced Al alloy matrix composites

A bimodal size metallic glassy particles reinforced 7075 aluminum composite was fabricated by powder metallurgy via ball milling and hot extrusion. The results show that metallic glassy reinforcements help to improve the densification due to the liquid-like behavior in the supercooled liquid region. The metallic glassy reinforcements were found to have a bimodal size distribution at nanoscale and microscale, and were uniformly distributed in the matrix. An interphase layer with a thickness of 60–80 nm was observed between the reinforcement/matrix resulted from elemental diffusion and chemical reaction. The introduction of bimodal size metallic glassy particles have significantly improved the mechanical properties, where the yield strength and fracture strength increase from 442 and 648 MPa for Al7075 to 869 and 962 MPa for composite with 17 vol% reinforcement, respectively. The strengthening mechanisms of the composites were revealed.

Sliding wear behaviour study of alumina-silicate short fiber reinforced AA2014-Al alloy composite (SFRAC)

In this study, short alumina-silicate fiber reinforced AA2014 Al-alloy matrix composite was prepared through squeeze infiltration technique. Dry sliding wear behaviour of the synthesized composite was carried out using a pin on disc under the application of varying loads (20–60 N) and velocities (2–4 m s−1) and the obtained results were compared with that of squeeze cast and gravity cast Al-alloy. The wear response of the investigated materials has been explained on the basis of microstructure, wear surface heating and wear-mechanism. The wear mechanism in composite has been explained schematically with supporting wear surface and subsurface micrographs. It is noted that composite suffered from relatively higher coefficient of friction, wear rate and frictional heating as compared to the alloys, irrespective of applied load and sliding speeds.

Microstructure and Mechanical Properties of Zr–Al–Ni–Cu Metallic Glassy Particles Reinforced 7056 Al Alloy Matrix Composites Obtained by Spark Plasma Sintering

New 7056 aluminum alloy matrix composites reinforced with Zr55Al10Ni5Cu30 metallic glassy particles are successfully fabricated by spark plasma sintering (SPS) combined with gas‐atomization method. The highly dense bulk body is obtained by utilizing the viscous flow behavior of the glassy powder within the supercooled liquid region. The addition of amorphous reinforcing phase significantly increases the yield strength of Al alloys in compression from 322 to 455 MPa, with retaining a fracture strain ranging between 26% and 16%. It is confirmed that the mutual diffusion of elements takes place between Al alloy matrix and glassy reinforcement during SPS process. The imposed stress and temperature by SPS affect the mutual diffusion and elemental distribution at interface. The increased mechanical response is ascribed to the uniform distribution of the glassy particles and good interfacial bonding. The mechanical properties of such composites can be accurately described by the iso‐stress model involving the matrix‐strengthening mechanism.

Variation of microstructure and mechanical properties of hybrid particulates reinforced Al-alloy matrix composites with ultrasonic treatment

The effects of ultrasonic treatment (UT) on the microstructure and mechanical properties of 10 wt% Mg2Si+1 wt% nano-sized SiC particles (SiCnp for short) hybrid reinforced Al-Cu alloy matrix composites were investigated for first time. The existence of Mg2Si phase solves the problem effectively that the particle content of SiCnp/Al-Cu composites cannot be high by the external addition of SiCnp and casting method. The results show that after UT, the big eutectic Mg2Si phase was remarkably refined, from coarse Chinese characters (about 50 μm) to fine strips or dots (about 0.5–2 μm). Meanwhile SiCnp agglomerations were also eliminated, and both Mg2Si phase and SiCnp were uniformly distributed in the composites. The interaction between Mg2Si and SiCnp was discussed to analyze this behavior that SiCnp could act as heterogeneous nucleus of Mg2Si phase, or be captured by the Mg2Si solid front during solidification, leading to the refinement of eutectic Mg2Si phase. It was also found that the effects of UT could be even improved by using squeeze casting (SC), instead of gravity casting (GC). The as-cast ultimate tensile strength (UTS) and elongation of hybrid Mg2Si + SiCnp/Al-Cu composites fabricated by combining UT and SC were enhanced to 336 MPa and 3.0%, which were increased by 31.3% and 130.8%, respectively, compared with the composites without UT. The UTS of the hybrid Mg2Si + SiCnp/Al-Cu composites was also 33.5% higher than that of the Al-Cu matrix alloy and 23.5% higher than that of 1 wt% SiCnp/Al-Cu composites prepared by the same process.

Dry Sliding Wear Behaviour study of Alumina-silicate Short Fiber Reinforced AA2014-Al Alloy composite

Abstract In this study, short alumina-silicate fiber reinforced AA2014 Al-alloy matrix composite was prepared through squeeze infiltration technique. Dry sliding wear behaviour of synthesized composite was carried out using pin on disc under varying applied loads (20-60 N), velocities (2 and 4 m/s) and compared with that of squeeze cast and gravity cast Al-alloy. The wear-response of the investigated materials has been explained on the basis of microstructures, wear surface heating and wear-mechanisms. The wear mechanism in composite has been explained schematically with supporting wear surface and subsurface micrographs. It is interestingly noted that the composite suffers from relatively higher coefficient of friction, the wear rate and frictional heating as compared to the alloys, irrespective of applied load and sliding speed.

Study of mechanical and wear characteristics of AL380 composite fabricated by introducing B4C using compo casting method

In the present work, Al380 Al alloy and B4C metal matrix composite was fabricated with different weight fractions (1%,2% and 3%) using compo-casting method. The wear properties of fabricated composite is tested by pin on disc apparatus. On different loads of 30N,60N and 90N the wear tests are performed. The mechanical properties of hardness and tensile strength are performed on brinell’s hardness apparatus and Ultimate tensile machine. The study of homogeneous distribution of B4C particles were examined by scanning electron microscope (SEM) in the composites. The result shows that the Al380 Al alloy reinforced with B4C particles, that composite improves the mechanical properties and wear rate. Increasing of wear rate with the increase in B4C particles in composites. Using Opti- cal microscope, the study of worn surfaces of pins were analyzed.