SiC Particle-reinforced Aluminum Matrix Composites Research Articles

Hot Deformation Behavior and Mechanisms of SiC Particle Reinforced Al-Zn-Mg-Cu Alloy Matrix Composites

A systematic and comprehensive analysis of the hot deformation and mechanisms of SiC particle-reinforced aluminum matrix composites is significant for optimizing the processing of the composites and obtaining the desired components. Based on this, related research on 11 vol% SiCp particle-reinforced 7050Al matrix composites was carried out. Hot compression experiments were carried out on the Gleeble-3500 thermal simulator to study the hot deformation behavior of composites at the temperature of 370–520 °C and strain rate of 0.001–10 s−1. The hyperbolic sine constitutive equation of the material was established, and the processing map was calculated. Combining the typical metallograph and misorientation angle distribution, the microstructure evolution mechanism of composites was analyzed, and the effect of particles on recrystallization behavior was investigated. Under certain process conditions, the dominant deformation mechanism of composites changed from dynamic recovery (DRV) to dynamic recrystallization (DRX), and the grain boundary sliding mechanism began to play a role. In addition, high temperature tensile and elongation at break were tested, and it was found that the dominant form of fracture failure changed from brittle fracture of the particles to ductile fracture of the matrix as the temperature increased.

Molten Pool Dynamics and Particle Migration Behavior during TIG-assisted Droplet Deposition Manufacturing of SiC Particle-reinforced Aluminum Matrix Composites

Molten Pool Dynamics and Particle Migration Behavior during TIG-assisted Droplet Deposition Manufacturing of SiC Particle-reinforced Aluminum Matrix Composites

Experiment and simulation of SiC particle-reinforced aluminum matrix composites fabricated by friction stir processing

The influence of the pre-implanted reinforced particles on the temperature field and the flow field of the processed zone directly determines the microstructure and properties of the aluminum matrix composites fabricated by friction stir processing (FSP). However, the differences in the characteristics of processed materials, especially the effect of pre-implanted reinforced particles on the flow of plastic materials, have rarely been reported. In this study, the temperature distribution of the processed zone was obtained by experimental measurement and numerical simulation. The model of the effect of the SiC particles as reinforced particles on the temperature field and the flow field of the processed zone was established. The influence of the SiC particles on the flow of plastic materials during the FSP was further investigated. The refinement, particle size, and distribution of the SiC particles in the processed zone of the FSPed multi-pass composites were also discussed in detail. The microhardness of the processed zone was also tested and discussed. The results showed that the temperature field at the contact interface between the SiC particles and the matrix in the processed zone was not continuously distributed. Due to the collision and hindrance of the reinforced SiC particles, the flow direction of plastic materials in the processed zone had been changed many times during the flow process. The initial average particle sizes of the SiC particles have a significant effect on the flow path of the processed plastic material. The microhardness of the processed zone of the FSPed specimens is significantly higher than that of the matrix.

Numerical Analysis of Particulate Migration Behavior within Molten Pool during TIG-Assisted Droplet Deposition Manufacturing of SiC Particle-Reinforced Aluminum Matrix Composites.

A transient three-dimensional (3D) numerical model was established to illustrate the heat transfer, fluid flow and particle migration behaviors in the molten pool during TIG-assisted droplet deposition manufacturing (DDM) of SiC particle-reinforced aluminum matrix composites (AMCs). The effect of temperature-dependent physical properties and the interaction between the SiC reinforcement and the liquid metal matrix were considered. A double-ellipsoidal volumetric heat source model was adopted to simulate the energy interactions between the pulse square-wave variable polarity TIG welding arc and the moving substrate. Free surface fluctuations of molten pool due to arc force and sequential droplet impact are calculated with volume of fluid (VOF) method in a fixed Eulerian structured mesh. The numerical model, capable of capturing the impact, simultaneous spread, and phase change of the droplets as well as the motion trajectory and terminate distribution state of the reinforcement particles, is key tool to understand the formation mechanism of the TIG-assisted DDM of SiC particle-reinforced AMCs. The numerical model was validated by the metallographic observations, and the calculated particle distribution and solidification morphology of deposited layer agree well with the experimental measurements.

Study of Nanoscale Wear of SiC/Al Nanocomposites Using Molecular Dynamics Simulations

In this work, molecular dynamics simulations are performed to investigate the nanoscale wear behavior of SiC particle-reinforced aluminum matrix composites (SiC/Al NCs) through nanoscratching using a spherical diamond indenter. A series of simulations are conducted to explore the effects of scratching depth, scratching speed, temperature, indenter size, and particle size during the nanoscratching process. We find the dislocation strengthening in the nanoscratching of SiC/Al NCs. It is also found that the frictional force and normal force increase with the increase of scratching depth, indenter size, and nanoparticle size. Moreover, the friction coefficient increases with the scratching depth. However, the friction coefficient declines with the increase of indenter size and nanoparticle size. Furthermore, for a larger scratching speed, the frictional force becomes smaller, while the normal force becomes larger, which is mainly determined by the competition between strain rate hardening and thermal softening. We also find that both the frictional force and normal force become smaller for a higher temperature resulting from thermal softening effect. The insights into the nanoscale wear properties of SiC/Al NCs lay a foundation for the wide applications of SiC/Al NCs.

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.

Effect of Zn and mechanical vibration agitation on the microstructure evolution in brazed joint of SiC particle-reinforced aluminum matrix composites

In order to broaden SiC particle-reinforced aluminum matrix composites in the applications of high-temperature and high-power electronic devices for electronics packaging, three types of the zinc-containing fillers and a low-frequency/low-amplitude mechanical vibration agitation technology were introduced for brazing of 10 vol.% and 70 vol.% SiCp/Al-MMCs. The effect of Zn element and mechanical vibration agitation on the microstructure of the joints was investigated. The increasing aluminum concentration and the decreasing zinc concentration in the bond seam were confirmed by the microstructure images, weight loss measurements, and EDS results and were attributed to zinc penetration and volatilization. Vaporization of zinc in the liquid filler increased the voids and number of vacancies, which destroyed the arrangement structure of liquid filler, namely, short-range order and long-range disorder, and facilitated the mutual diffusion of other atoms. The joints of 70 vol.% SiCp/A356-MMCs with a shear strength of 16.6 MPa were produced at 480 °C and 0.5 MPa using Zn-25Al-10Ga-9Mg-1Ti interlayer. For 10 vol.% SiCp/A356-MMCs, sound joints with a shear strength of 119 MPa were obtained at 520 °C using the Zn-5Al-4Mg foil. Cracks are initiated from the particle/metal (P/M) interface and subsequently propagated to the matrix/metal (M/M) interface. Mg-Si-rich phases were observed in the bond seam and at the interface of 70 vol.% SiCp/Al-MMCs with different Mg content interlayers, which was also a weak interface for the joint. The results also indicated that the active element Mg in the filler should be controlled to an appropriate content for brazing of high volume fraction composites.

Investigation on cutting mechanism of SiCp/Al composites in precision turning

This paper investigates the underlying cutting mechanism of SiC particle-reinforced aluminum matrix composites (MMCs) using finite element (FE) simulations and precision turning experiments. One constitutive model for SiCp/Al composites is established and verified by experiments. On this basis, the possible fracture processes of SiC particles in turning process are studied, and three types of fracture are finally found. The types and the corresponding formation mechanism of machined surface defects are investigated; the relationship between the particle size and surface roughness is established quantitatively. Furthermore, the influences of machining parameters on the cutting force are studied. The proposed FE simulation model and conclusion are verified by precision turning experiments.

An investigation of the influence of phases’ removal ways on surface quality in micro milling SiCp/Al composites

SiC particle-reinforced aluminum matrix (SiCp/Al) composites are widely employed due to their outstanding performance. However, since they are composed of brittle SiC and ductile aluminum, the different removal mechanisms of the two phases may affect the surface quality in micro milling. In this paper, an experimental investigation of micro milling a kind of 45% SiCp/Al composites is presented. Using different values of the feed rate, the changes of the removal ways of the two phases are shown by 3D surface roughness and surface morphology. The results indicate that the surface roughness decreases firstly and increases later with the feed rate growing, which may be caused by the change of the removal way of the particle. A criterion for that is built. SEM pictures show that the surface is significantly coated by aluminum matrix when the feed rate is small; as the feed rate increases, the coating effect of the matrix weakens, and the removal ways of the particle changes from ductile regime machining to brittle fracture. Smaller feed rate may lead to the incompletely removing (plowing) of the Al and make the soft matrix coat the surface, while larger feed rate may result in the particle fracture, producing large numbers of cracks and damaging the surface integrity. Using suitable feed rate, the Al matrix can be removed efficiently and the SiC particle can be cut in its ductile regime. The unit of the suitable removal ways of Al matrix and SiC particle in machining process can produce a better surface.

A study of grinding forces of SiCp/Al composites

In this study, the grinding experiments were conducted on SiC particle-reinforced aluminum matrix (SiCp/Al) composites under wet, dry, cryogenic, and ELID grinding conditions, and the effects of grinding depth and table speed on grinding forces and grinding force ratio were investigated. The experimental results showed that both the normal and tangential grinding forces of SiCp/Al composites increased evidently with the increasing of the grinding depth and table speed under the four grinding conditions. And the grinding forces under the cryogenic condition were the largest, the grinding forces under the dry condition were the second, and the grinding forces under the wet condition were the minimum. Additionally, the grinding force ratio values decreased with the increase of grinding depth under the wet and dry conditions, while the grinding force ratio values increased slightly with the increase of the grinding depth under the cryogenic and ELID grinding conditions. The grinding force ratio was minimum under ELID grinding condition.

Improving the particle distribution and mechanical properties of friction-stir-welded composites by using a smooth pin tool

Friction stir welding (FSW) is a very promising technique for joining particle-reinforced aluminum-matrix composites (PRAMCs), but with increase in the volume fraction of reinforcing particles, their distribution in welds becomes inhomogeneous. This leads to an inconsistent deformation of welds and their destruction at low stresses. In order to improve the weld microstructure, a smooth pin tool was used for the friction stir welding of AC4A + 30 vol.% SiC particle-reinforced aluminum-matrix composites. The present work describes the effect of welding parameters on the characteristics of particle distribution and the mechanical properties of welds. The ultimate strength of weld reached, 309 MPa, was almost 190% of that of the basic material. The mechanism of SiC particle conglomeration is clearly illustrated by means of schematic illustrations.

Simulation study of the influence of cutting speed and tool–particle interaction location on surface formation mechanism in micromachining SiCp/Al composites

The SiC particle-reinforced aluminum matrix composites are widely employed in different fields due to their outstanding performance. An in-depth understanding of their surface formation mechanism will pave a solid foundation for the widespread application. In this paper, two-dimensional microscale finite element models composed of a SiC particle and Al2024 matrix are established. The effects of cutting speed and tool–particle interaction location on particle behavior and surface formation during micromachining process are investigated. The location is categorized into two scenarios (tool cuts the upper and the lower part of the particle) and different cutting speeds for each scenario are presented. As a result, in scenario one (tool cuts the upper of the particle), the particle fractures by brittle fracture while the depth of surface defects decreases with increase of the cutting speed; in scenario two (tool cuts the lower part), the removal way of the particle changes from being pulled out to being crushed as the speed increases. The von Mises equivalent stresses of the particle and the matrix at the two scenarios are analyzed to explain these phenomena. Experimental measurements of micromilled surfaces are compared with simulation, showing promising results.

A new approach for preparing SiC particle-reinforced aluminum matrix composites by applying electromagnetic field

A new method for preparing SiC particle-reinforced aluminum matrix composites was introduced. In order to improve the ingot surface and homogeneity of structure, low frequency electromagnetic field was applied during the direct chilling casting process. The experimental results show that the new method can be used to prepare SiC particle-reinforced aluminum matrix composites; under the effects of the low frequency electromagnetic field, the microstructure of ingot is refined and the distribution of SiC particles is improved.

Compressive Properties of SiC Particle-Reinforced Aluminum Matrix Composites Under Repeated Impact Loading

Under repeated impact loading, SiC particle-reinforced aluminum matrix composites (SiCp/Al) experience severe plastic strains, which can lead to local changes in their microstructure. Microstructural variations have a significant effect on the dynamic behavior of SiCp/Al composites under subsequent impact loading. Their microstructure was analyzed by scanning electron microscopy (SEM). Then the dynamic compressive properties of SiCp/Al composites were studied using the split Hopkinson pressure bar (SHPB), and the dynamic compression stress–strain curve for each impact was plotted. The SEM results revealed that an increase in the impact cycle led to enhanced cracking of particles and interface delamination. The SHPB results showed that the yield stress and flow stress increased significantly for the first three cycles and then remained constant. The material behavior during the first three cycles can be attributed to strain hardening of the metal matrix, while its stability at the subsequent stages is the combined effect of strain hardening of the metal matrix and damage accumulation in the composite.

Cutting Simulations and Experiments of Milled SiC Particle-Reinforced Aluminum Matrix Composites

When SiC particles are added into aluminum, property of aluminum is greatly improved during a reinforcing phase to produce particle reinforced aluminum composites. However, cutting tools wear out quickly and it is difficult to meet machining accuracy and surface quality requirements due to the rough surface produced by the reinforcement process. This paper presents a simulation model of SiC particle-reinforced aluminum matrix composites is established considering particles, cohesive elements, and material matrix. Stress distribution and surface roughness are analyzed for SiC/Al matrix composites based on the cutting process. Experiments are performed to test the degree of surface roughness using different cutting parameters. The relationship of cutting depth, cutting velocity, and feed rate per tooth to surface roughness degree is obtained for SiC/Al matrix composites. The optimization of cutting process is performed based on simulation. The results lay a foundation on the optimization of machining processes for metal matrix composites.

Friction and Wear Properties of Aluminum Matrix Composites and its Application

Friction and wear properties of aluminum matrix composites are studied, including brake speed, brake pressure, and surface temperature etc. A conclusion can be drawn that SiC particle reinforced aluminum matrix composites are of stable friction coefficient, high thermal conductivity, and excellent wear-resistance. Hubs of motorcycle with brake rings of Al/SiC composites were manufactured and exhibited an excellent braking performance.

Light Weight and High Modulus Aluminum Matrix Composite and its Application into Aerospace

Compared to the conventional constructive materials, SiC particle reinforced aluminum matrix composites have lighter weight and higher specific modulus, and are applied in the structure framework of solar battery array for space station. According to the requests of the material properties for this framework, aluminum matrix composites are specially designed and manufactured, and then deformed into components of different shapes and sizes for various uses. The composite components were of compact structure and excellent mechanical properties, and had passed all the application tests for the framework. The application of aluminum matrix composites achieves a good result that not only the framework weight was greatly reduced but also the comprehensive properties of the framework were improved greatly. Aluminum matrix composites exhibit a great potential for further application into aerospace.

Effect of Particle Diameter and Volume Fraction on Wear Behaviour of SiC-Particle Reinforced Aluminum Matrix Composites

The wear behavior of SiC-particle reinforced aluminum matrix composites (MMCp) was investigated by pin-on-disk tests under atmosphic conditions. The matrix material was 2024 aluminum alloy. The SiC particles were between 2 and 10 μm in diameter (d) with volume fractions (Vf) between 2 and 10%. The MMCp of the disk were rubbed against the 0.45% carbon steel of the pin witha load of 10N at a sliding velocity of 0.1m/s. The steady-state wear rate of MMCp decreased with increasing d and Vf, On the other hand, the wear rate of the steel counterface increased with increasing d and Vf. The wear rate was affected by two factors; one is the effect of reinforced particles against adhesive wear, and the other is the abrasive action of reinforcements. As a result, it was concluded that d=5μm, Vf=5, 10% provide the highest wear resistance for MMCp in this study.

Microstructure Characteristics of SiC Particle-Reinforced Aluminum Matrix Composites by Plasma Spraying

Aluminum with 55 and 75 vol.% SiC powders were ball milled as plasma spray feedstock. The feedstock was deposited onto a graphite substrate to form a freestanding composite by air plasma spraying. The microstructure characteristics of the sprayed composite were investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The SiC volume fraction and porosity in the sprayed composites depend on plasma spray conditions. The silicon phase was formed in the sprayed composites in some plasma spray conditions, and its amount was related to the input of electrical power into the plasma spray. The mechanism of silicon formation was studied. In the sprayed composites, no reaction products could be observed in the Al/SiC interface. Impurity materials from ball media, stainless steel, and ZrO2 reacted with aluminum and silicon to form complex compounds during plasma spray deposition.

Electrical and thermal conductivity of discontinuously reinforced aluminum composites at sub-ambient temperatures

The electrical and thermal conductivities of two SiC particle-reinforced aluminum-matrix composites were measured over the temperature range of 80–300 K. Because of the relatively low value of electrical conductivity of the SiC, the composite conductivity data agreed closely with those of the matrix with spherical pores, as predicted by the theory of Maxwell. The experimental data for the thermal conductivity of the composite exceeded the values predicted for the matrix phase with spherical holes, indicative of a contribution by the silicon carbide reinforcement. This contribution was significant at the higher temperatures but approached zero at the lowest temperature levels. Data analysis suggested that this effect could be attributed to a decrease in the thermal conductance at the AlSiC interface with decreasing temperature, due to a corresponding increase in phonon scattering or other mechanisms.