Particle Reinforced Aluminum Matrix Composites Research Articles

Characterization of physical and mechanical properties of aluminium based composites reinforced with titanium diboride particulates

Particulate reinforced aluminium matrix composites are one of the most attractive approaches for applications where high strength and hardness combinations are necessary. The aspiration of this study is to investigate the effect of titanium diboride addition on physical and mechanical properties of Al2024-TiB2 composites manufactured using stir casting route, by varying the weight percentages (wt.%) (0, 3, 6 and 9 percent) of titanium diboride particulates. During the casting process, stirring time and speed were kept constant and same for all the composites. Microstructural analysis demonstrates uniformity in TiB2 distribution and also strong matrix-reinforcement bonding which can be as a result of magnesium addition and preheating of titanium diboride particles before incorporating into the molten aluminium. With an increment in the wt.% of TiB2 particulates, hardness and tensile strength of the prepared composites improved, a significant improvement in hardness as well as tensile strength is encountered in Al2024-9% TiB2 composite, which is 44.94% and 35.49% higher than Al2024 matrix alloy, respectively. SEM analysis of the fractured surfaces revealed that the mode of fracture of unreinforced material is purely ductile but reinforced material fractured by nucleation of cracks and plastic deformation.

Joining high volume fraction SiC particle reinforced aluminum matrix composites (SiCp/Al) by low melting point stannous oxide–zinc oxide–phosphorus pentoxide glass

This study focused on joining high volume fraction SiC particles reinforced aluminum matrix composites (55 vol% SiCp/Al) with 50SnO–20ZnO–30P2O5 (SZP) glass directly in air. Prior to joining, various properties of the SZP glass and its wettability on the composites were investigated. The results showed that the coefficient of thermal expansion of the glass was 10.58 × 10-6/°C (20–369 °C), which closely match with 55 vol% SiCp/Al composites. The glass transition, crystallization, and softening temperature were identified to be 369, 397, and 486 °C, respectively. Subsequent wetting tests confirmed excellent wettability of the glass on the composites. The joint exhibited sound bonding that was free of defects when brazed at 550 °C for 10 min Zn2P2O7 was formed adjacent to the composites due to the crystallization of the glass. The mechanical properties of the joint were proven to be suitable, exhibiting an average shear strength of 55.3 MPa.

Investigation on surface roughness in axial ultrasonic vibration–assisted milling of in situ TiB2/7050Al MMCs

The surface roughness is one of the important parameters of surface quality evaluation. In the field of aerospace and industry, many attempts have been made to reduce the roughness of machined surface and improve the performance of parts. An advanced manufacture technique, ultrasonic vibration–assisted milling, can reduce the surface roughness, which is widely used to cut the materials that are difficult to machine. In this work, the theory of the machined surface generation is analyzed and the effect of cutting parameters and the ultrasonic vibration on the machined surface is investigated by ultrasonic vibration–assisted milling of in situ TiB2 particle–reinforced aluminum matrix composite. Firstly, the motion trajectory of cutting tool and machined surface topography generation is analyzed theoretically. Then, theoretical model of the number of vibration per cutting arc length and the transient angle is built to analyze the generation of the surface topography. Finally, experiments with and without ultrasonic vibration are carried out for the theoretical analysis of the machined surface generation and the surface roughness. The results show that regular micro-dimples are produced on the machined surface due to the addition of ultrasonic vibration and the theoretical model could be applied to explain the influence of ultrasonic vibration on the surface topography and roughness. Besides, in this study, the assistance of ultrasonic vibration can improve the surface quality in certain cutting conditions of cutting speed below 65.94 m/min and the vibration frequency of 20 kHz.

A review of particulate-reinforced aluminum matrix composites fabricated by selective laser melting

Selective laser melting (SLM) is an emerging layer-wise additive manufacturing technique that can generate complex components with high performance. Particulate-reinforced aluminum matrix composites (PAMCs) are important materials for various applications due to the combined properties of Al matrix and reinforcements. Considering the advantages of SLM technology and PAMCs, the novel SLM PAMCs have been developed and researched in recent years. Therefore, the current research progress about the SLM PAMCs is reviewed. Firstly, special attention is paid to the solidification behavior of SLM PAMCs. Secondly, the important issues about the design and fabrication of high-performance SLM PAMCs, including the selection of reinforcement, the influence of parameters on the processing and microstructure, the defect evolution and phase control, are highlighted and discussed comprehensively. Thirdly, the performance and strengthening mechanism of SLM PAMCs are systematically figured out. Finally, future directions are pointed out on the advancement of high-performance SLM PAMCs.

Ceramic waste SiC particle-reinforced Al matrix composite brake materials with a high friction coefficient

We investigated wear behavior of ceramic waste SiC particle-reinforced aluminum matrix composites (ASC) to evaluate the effect of hybrid particles on dry sliding. Aluminum alloy and its composites were prepared by powder metallurgy process. Brinell hardness and flexural strength of ASC are improved compared to those of the aluminum base alloy. When the load increases to 80 N, the friction coefficient of ASC increases by 32% compared to that of only SiC-reinforced aluminum matrix composites. The wear rate is similar to that of the SiC-reinforced aluminum matrix composites, and only 1/15 of that of the conventional brake disc material (HT250). Results of scanning electron microscopy, X-ray photoelectron spectroscopy, and grazing incidence X-ray diffraction showed that the ceramic waste particles are involved in the formation of a mechanical transfer layer of ASC. This layer is favorable for the preservation of ultrafine wear debris over the worn surface. Hybrid particles effectively protect the matrix and provide a high friction coefficient. ASC is a potential candidate material for high-performance brake discs.

Joining of Silicon Particle-Reinforced Aluminum Matrix Composites to Kovar Alloys Using Active Melt-Spun Ribbons in Vacuum Conditions

The vacuum brazing of dissimilar electronic packaging materials has been investigated. In this research, this applies silicon particle-reinforced aluminum matrix composites (Sip/Al MMCs) to Kovar alloys. Active melt-spun ribbons were employed as brazing filler metals under different joining temperatures and times. The results showed that the maximum joint shear strength of 96.62 MPa was achieved when the joint was made using Al-7.5Si-23.0Cu-2.0Ni-1.0Ti as the brazing filler metal at 580 °C for 30 min. X-ray diffraction (XRD) analysis of the joint indicated that the main phases were composed of Al, Si and intermetallics, including CuAl, TiFeSi, TiNiSi and Al3Ti. When the brazing temperature ranged from 570 °C to 590 °C, the leakage rate of joints remained at 10−8 Pa·m3/s or better. When the joint was made using Al-7.5Si-23.0Cu-2.0Ni-2.5Ti as the brazing filler metal at 580 °C for 30 min, the higher level of Ti content in the brazing filler metal resulted in the formation of a flake-like Ti(AlSi)3 intermetallic phase with an average size of 7 µm at the interface between the brazing seam and Sip/Al MMCs. The joint fracture was generally in the form of quasi-cleavage fracture, which primarily occurred at the interface between the filler metal and the Sip/Al MMCs. The micro-crack propagated not only Ti(AlSi)3, but also the Si particles in the substrate.

Effects of in-situ TiB2 particles on machinability and surface integrity in milling of TiB2/2024 and TiB2/7075 Al composites

In-situ ceramics particle reinforced aluminum matrix composites are favored in the aerospace industry due to excellent properties. However, the hard ceramic particles as the reinforcement phase bring challenges to machining. To study the effect of in-situ TiB2 particles on machinability and surface integrity of TiB2/2024 composite and TiB2/7075 composite, milling experiments were performed, and compared with conventional 2024 and 7075 aluminum alloys. In-situ TiB2 particles clustered at the grain boundaries and dispersed inside the matrix alloy grains hinder the dislocation movement of the matrix alloy. Therefore, the milling force and temperature of the composites are higher than those of the aluminum alloys due to the increase of the strength and the decrease of the plasticity. In the milling of composites, abrasive wear is the main wear form of carbide tools, due to the scratching of hard nano-TiB2 particles. The composites containing in-situ TiB2 particles have machining defects such as smearing, micro-scratches, micro-pits and tail on the machined surface. However, in-situ TiB2 particles impede the plastic deformation of the composites, which greatly reduces cutting edge marks on the machined surface. Therefore, under the same milling parameters, the surface roughness of TiB2/2024 composite and TiB2/7075 composite is much less than that of 2024 and 7075 aluminum alloy respectively. Under the milling conditions of this experiment, the machined subsurface has no metamorphic layer, and the microhardness of the machined surface is almost the same as that of the material. Besides, compared with 2024 and 7075 aluminum alloy, machined surfaces of TiB2/2024 composite and TiB2/7075 composite both show tensile residual stress or low magnitude of compressive residual stress.

Hot-Deformation Behavior and Microstructure Evolution of the Dual-Scale SiCp/A356 Composites Based on Optimal Hot-Processing Parameters.

Hot deformation at elevated temperature is essential to densify particle-reinforced aluminum matrix composites (AMCs) and improve their performance. However, hot deformation behavior of the AMCs is sensitive to the variation of hot-processing parameters. In this paper, optimal processing parameters of dual-scale SiCp/A356 composites were determined to explore the control strategy of the microstructure. Hot-compression tests were conducted at temperatures ranging from 460 to 520 °C under strain rates from 0.01 to 5 s−1. Constitutive equation and processing maps were presented to determine the hot-processing parameters. Microstructure evolution of the dual-scale SiCp/A356 composites was analyzed. The strain rate of 0.62–5 s−1 and deformation temperature of 495–518 °C is suitable for the hot processing. The number of dynamic recrystallization (DRX) grains in the “safe” domains is larger and the dislocation density is lower compared to those of instability domains. DRX grains mainly occurred around SiC particles. The presence of SiC particles can promote effectively the DRX nucleation, which results in the dynamic softening mechanism of the dual-scale SiCp/A356 composites being dominated by DRX.

An analytical model for force prediction in micromilling silicon carbide particle–reinforced aluminum matrix composites

In micromilling the silicon carbide particle–reinforced aluminum matrix composites, cutting forces can provide a better insight of the cutting mechanism. In this article, an analytical model for force prediction in micromilling composites is developed considering the size effect of the matrix. In modeling, for the matrix, the cutting area is divided into shearing area and plowing area and the removal forces are established considering chip formation and edge forces; for the particle, the removal forces are established based on Griffith fracture theory. The model is verified by micromilling experiments. The influences of the process parameters (milling width, milling depth, and feed per tooth) on the milling force were studied. It shows that the maximum milling force increased with the increase in the feed per tooth and the milling depth and increases first and then stabilizes with the increase in milling width; the average milling force increases with the increase in the three parameters. In addition, the contribution of the particle fracture force is analyzed, and it is found that the contribution of the particle fracture force is affected by the feed per tooth, which basically accounts for about 23% of the maximum milling force and accounts for 23%–30% of the average milling force.

AlCoCrFeNi high-entropy alloy particle reinforced 5083Al matrix composites with fine grain structure fabricated by submerged friction stir processing

In the present work, 5083Al matrix composites reinforced by 10 vol% AlCoCrFeNi high-entropy alloy (HEA) particles were fabricated by submerged friction stir processing (SFSP). It was found that the fabricated composites consist of equiaxed fine grains with the mean size of 1.2 μm due to dynamic recrystallization, particle stimulated nucleation (PSN) and shortened thermal cycle by water cooling. The HEA/5083Al interface showed a two-layer structure, the layer close to the HEA exhibited FCC + T phases with the thickness of approximately100 nm, and the other layer consisted of the Cr-depleted AlCoCrFeNi HEA particles in the size of roughly 100 nm. The SFSPed HEA/5083Al composites showed 25.1% higher yield stress (YS) and 31.9% higher ultimate tensile strength (UTS) in comparison with the base metal while maintaining acceptable ductility (18.9%). Grain refinement, geometrically necessary dislocations and load transfer effect can mainly be responsible for the improved strength. • SFSP were conducted on AlCoCrFeNi high entropy particles reinforced aluminum matrix composites. • CDRX, PSN and shortened thermal cycle by water cooling can be responsible for the grain refinement. • The interface structure was characterized to investigate the interface formation mechanism.

Effect of SiC Defects on Performance of Particle Reinforced Aluminum Matrix Composites

The effect of segregation defect of SiC particles on the properties of materials was studied. 15% SiCp/2009Al composites were prepared by powder metallurgy (PM). Special SiC/Al samples were added to 15% SiCp/2009Al composites. These SiC/Al samples with different sizes and volume fractions were 25%, 35%, 45% and 60%, respectively, which resulted in SiC particulates segregation defect. The 15% SiCp/2009Al composites with defects were tested by ultrasonic testing. Tensile samples were obtained at the locations, where defects might be detected and the mechanical properties were tested. The results showed that all defective samples were cracked at the defective location. The difference in tensile strength between the samples of defect and the samples without defect was large. The toughness of the sample containing the defect reduced and the brittleness increased. The dimples on the matrix indicate that ductile fracture occurred during the fracture process. The cleavage fracture or cracking of the SiC particulates indicated that the stress can be effectively transferred from the matrix to the particles, and the particulates strengthen the matrix well. However, the sample with defect led to brittle fracture in the defect, and a crack source produced at the interface, resulting in a significant decrease in the mechanical properties of the material. If the inhomogeneous distribution of particulate containing a large area was found in the ultrasonic testing of the aluminum matrix composites, the tensile properties of the products generally cannot meet the requirement for application.

Physico-chemical and morphological evaluation of palm kernel shell particulate reinforced aluminium matrix composites

The superior physical and mechanical properties of metals matrix composites in comparison to the matrix metals over a wide range of operating conditions makes them an attractive option in replacing metals for various engineering applications. In the present investigation, Aluminium alloy 6063 was reinforced with varying weight percentage of 212 µm palm kernel shell (PKS) particles (2.5%, 5%, 7.5%, 10%, 12.5% and 15%). The composite was prepared in a mild steel permanent mould, using stir-casting technique. Some chemical, physical and microstructural properties (XRF, XRD, density, % porosity and SEM-EDX) of the composites produced were characterized, evaluated and compared with that of the matrix alloy. The structural assessment evaluation of the reinforcement revealed the presence of elements and oxides that could improve the structure, physical and the mechanical properties of the composites. The morphological investigation showed that the secondary phase of PKS reinforcements were dispersed homogeneously in the Aluminium Matrix primary phase. The reinforcement of PKS particles improved the density of the produced composite over that of the base alloy, while the percentage porosity of the composites increased with increase in palm kernel shell content but lies within the maximum permissible limit for cast aluminium metal matrix composites. Formation of intermetallic compounds was evident in the composites developed.

Effect of Ultrasonic Vibration Tensile on the Mechanical Properties of High-Volume Fraction SiCp/Al Composite

Silicon carbide particle-reinforced aluminum matrix composite has been widely used in the military and aerospace industry due to its special performance; however, there remain many problems in processing. The present paper introduces an ultrasonic vibration tensile device with a view to investigating an ultrasonic vibration tensile specimen. The results show that there are three major stages in the change in stress of the material under ultrasonic vibration: the ultrasonic stress superposition effect, softening effect, and Hall–Petch strengthening effect, these three effects occupy different proportions in different tensile stages. In addition, increasing the frequency of ultrasonic vibration increased the degree of stress reduction. Increasing the ultrasonic vibration amplitude reduced the fracture strength of the material. Comparison of the fracture morphology shows that the conventional condition was mainly interfacial peeling of SiC particles, and cleavage of the fracture occurred under ultrasonic vibration conditions.

Tool wear mechanisms in axial ultrasonic vibration assisted milling in-situ TiB2/7050Al metal matrix composites

The in-situ TiB2 particle reinforced aluminum matrix composites are materials that are difficult to machine, owing to hard ceramic particles in the matrix. In the milling process, the polycrystalline diamond (PCD) tools are used for machining these materials instead of carbide cutting tools, which significantly increase the machining cost. In this study, ultrasonic vibration method was applied for milling in-situ TiB2/7050Al metal matrix composites using a TiAlN coated carbide end milling tool. To completely understand the tool wear mechanism in ultrasonic-vibration assisted milling (UAM), the relative motion of the cutting tool and interaction of workpiece-tool-chip contact interface was analyzed in detail. Additionally, a comparative experimental study with and without ultrasonic vibration was carried out to investigate the influences of ultrasonic vibration and cutting parameters on the cutting force, tool life and tool wear mechanism. The results show that the motion of the cutting tool relative to the chip changes periodically in the helical direction and the separation of tool and chip occurs in the transverse direction in one vibration period, in ultrasonic vibration assisted cutting. Large instantaneous acceleration can be obtained in axial ultrasonic vibration milling. The cutting force in axial direction is significantly reduced by 42%–57%, 40%–57% and 44%–54%, at different cutting speeds, feed rates and cutting depths, respectively, compared with that in conventional milling. Additionally, the tool life is prolonged approximately 2–5 times when the ultrasonic vibration method is applied. The tool wear pattern micro-cracks are only found in UAM. These might be of great importance for future research in order to understand the cutting mechanisms in UAM of in-situ TiB2/7050Al metal matrix composites.

Investigation of Reinforced Particulate Flow and Distribution during Stirring Preparation of A356/SiCp with Experiment and Multi-phase Flow Simulation

Particulate-reinforced aluminum matrix composites produced by stirring casting method exhibit many advantages and are usually used in practical industries. The particulate flow and distribution during the stirring have significant effects on composite casting properties and performances. In this investigation, to study the effect of stirring parameters on particulate distribution, an experimental quenching apparatus was designed, and then A356/50μmSiCp prepared with different stirring speeds and positions were carried out. The particulate fractions at different locations of the prepared composites were quantitatively measured with micro-image analysis, and the charts of particulate distribution along axial directions were summarized and analyzed. Based on liquid-solid multiphase flow theory and multiple rotating reference frame models, a mathematical model of particulate-reinforced aluminum matrix composites stirring process established with consideration of relative flow between liquid and solid particle phases was applied to the experimental composite preparation. By comparing the simulation and experimental results, the effect of stirring condition on the composite slurry and particulate flow as well as the final particulate distribution were analyzed. The comparison shows that the simulated particle distribution exhibits well agreement with the experiment, indicating the validity and exactitude of the established model and method for actual composite stirring preparation. The study shows that low position of impeller would force more particles at the bottom region to flow with composite slurry, improving the particle distribution, and that high stirring speed can cause strong centrifugal force and radial flow of both composite slurry and particles, decreasing the particle uniformity in the composites.

Finite element investigation on the wave-particle interactions in ultrasonic inspection of SiCp/Al composites

While particulate-reinforced metal matrix composites are composed of two phase materials with dramatically different physical and mechanical properties, sound wave-particle interactions play an important role in their ultrasonic inspection tests. In the present work, we investigate the sound wave-particle interactions in silicon carbide (SiC) particle-reinforced aluminum (Al) matrix composites under the pulse-echo mode ultrasonic inspection by means of finite element simulations. Be consistent with experimentally observed real microstructures, the simulated SiC particles have polygon shapes and are randomly dispersed in the Al matrix. In particular, the sound wave-particle interactions are revealed, and their correlations with the A-scan signals are investigated. Furthermore, the effects of extrinsic pulse frequency and intrinsic SiC particle size on the ultrasonic inspection of the composites are addressed. Simulation results indicate that the interference of sound waves with heterogeneous SiC particles leads to more pronounced deflection, scattering and conversion of sound waves than the pure Al matrix, which in turn result in higher attenuation of sound waves in SiCp/Al composites. It is also found that the sound wave-particle interactions have a strong dependence on both pulse frequency and particle size.

Mechanical and Wear Behaviour of Severe Plastic Deformed Al6063-Nano Al2O3 Composites Processed by Constrained Groove Pressing (CGP)

Metal matrix composites have been developed to meet the demand for lighter materials with high specific strength, stiffness and wear resistance. Particulate reinforced aluminium matrix composites are attractive materials due to their strength, ductility and toughness. The aluminium matrix is strengthened when it is reinforced with hard ceramic phases. Most of the metal matrix compound undergoes severe plastic deformation (SPD). SPD is a method to obtain fine crystalline structure in different bulk metals and alloys which possess different crystalline structure. The objective of the present work is to synthesize Al-6063 alloy by stir casting method and varying weight percentage of nano Al2O3 in steps of 2, 4, and 6 wt %. The composites are prepared using the process of compressed groove pressing (CGP) with extreme plastic deformation. The composite is characterized for mechanical and wear behaviour. SEM microphotographs confirmed the distribution of nano Al2O3 particles in the Al6063 Matrix alloy. In addition, SEM micrographs of Al6063 alloy with nano Al2O3 after constrained groove pressing shown grain refinement. Improvements in Hardness, UTS, yield strength, bending strength, percentage elongation and wear resistance of the Al-6063 matrix are obtained with the addition of Al2O3 particulates and also the properties are further enhanced with CGP. The developed metal matrix nano composite may be an alternative material for manufacturing of bearings.

Effect of heat treatment on the interface of high-entropy alloy particles reinforced aluminum matrix composites

In this paper, high entropy alloy particles reinforced 5052 aluminum matrix composites were successfully prepared by vacuum hot pressing sintering technology. Interface layers with different thickness were formed in the composites by heat treatment. The effects of heat treatment temperature and time on the interface layer of composites were systematically studied by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), X-ray diffraction (XRD), electron probe microanalysis (EPMA) and nano-indentation. The results show that the new core-shell structure particles are dominant in the composites with long holding time at 500 °C heat treatment. Hardness and Young’s modulus of the composites are obviously improved by the generation of the interface layer. With the increase of heat treatment time, the thickness of the interface layer increases, and the discontinuous interface layer will obviously increase the hardness and Young’s modulus of the composites, which is related to the stress concentration and the bonding degree between the interface and the matrix.

超声处理对SiC颗粒增强铝基复合材料微结构与性能的影响

超声处理对SiC颗粒增强铝基复合材料微结构与性能的影响

Experimental study on cutting parameters and machining paths of SiCp/Al composite thin-walled workpieces

Thin-walled workpieces of silicon carbide particle-reinforced aluminum matrix (SiCp/Al) composites with outstanding properties have been widely applied in many fields, such as automobile, weapons, and aerospace. However, the thin-walled workpieces exhibit poor rigidity, large yield ratio, and easily deform under the cutting force and cutting heat during the machining process. Herein, in order to improve the processing efficiency and precision of higher volume fraction SiCp/Al composite thin-walled workpieces, the influence of different high-speed milling parameters and machining paths on the edge defects is analyzed. The results reveal that the cutting force initially increased and then decreased with the cutting speed. Besides, the cutting force steadily increased with radial cutting depth and feed per tooth, but the influence of feed per tooth is less than radial cutting depth. After up-milling cut-in and cut-out processing and down-milling cut-out processing, the cut-in end of the workpiece exhibited higher breakage and obvious edge defects. However, the workpiece edges remained intact after down-milling cut-in processing. In conclusion, a higher cutting speed, a smaller radial cutting depth, and moderate feed per tooth are required to decrease the cutting force during the milling of SiCp/Al composite thin-walled workpiece. Furthermore, down-milling cut-in processing mode can reduce the edge defects and improve the processing efficiency and precision of the workpiece.