SiC Particle Reinforced Metal Matrix Research Articles

Study on the Constitutive Model of SiCp/Al Composites

By conducting the quasi-static compression and split Hopkinson pressure bar testing,the flow strain - stress curves under strain rate range of 0.0001-1000/s and temperature range of normal-400°C of different volume fraction SiC particles reinforced metal matrix composite SiCp/6063Al were obtained. The commonly used Johnson-Cook constitutive model in metal materials was applied in this research. And on the basis of it, the influence of volume fraction to flow stress was utilized to establish the equivalent and homogeneous constitutive model.

Experimental Studies and Computer Simulation of Permeability Determination of Porous SiC Preforms

Permeability of SiC preform is a key parameter during the pressure infiltration studies of molten metal (Copper and Aluminium alloy) into porous SiC preforms during preparation of SiC particle reinforced metal matrix composites (MMC) with high content of SiC reinforcement. Its characterization could be quite helpful to reveal the defect formation mechanism of the composite productions and further optimize the preparation processes of such composites. The objectives of this study were to assess the pore distribution and determine the permeability of porous SiC preforms. We compared the values of permeability obtained from experimental data, calculation by Carman-Kozeny equation and simulation of micro-models. The results of experiment illustrated that permeability were 0.64 × 10-12 m2 (ε=30%), 1.76 × 10-12 m2 (ε=37%) and 10.20 × 10-12 m2 (ε=44%) respectively, which are quite similar to the value both of calculation and computer simulation. Additionally, results indicate that the permeability substantially affected by porosity and both size and shape of filling particles into SiC preform.

An investigation of cutting force and tool–work interface temperature in milling of Al–SiCp metal matrix composite

Aluminium–SiC particulate metal matrix composites have attracted much interest in recent years among practitioners and researchers in the field of aerospace, automobile, nuclear, electronic packaging and other industries due to their low coefficient of thermal expansion, high strength and stiffness, hardness, wear and corrosion resistance properties. The present study focuses on aluminium A356 alloy with four different volume % of SiC particle–reinforced metal matrix composites synthesized by vacuum hot-pressing technique to achieve uniform dispersion of finer reinforcement over the matrix with higher densification. In order to study the machinability issues of the developed composites, computer numerical control end milling studies were conducted using central composite experimental design by varying cutting speed, feed and depth of cut, and the responses such as cutting forces and tool–work interface temperature were measured. The effect of machining parameters and reinforcement on the matrix during machining was analysed and optimized, which gives valuable guidelines to the manufacturing industries. The response surface models were developed and compared with experimental results. The results show that increase in volume % of SiCp reinforcement over the matrix results in higher tool–work interface temperature and needs higher cutting force during machining process.

Effect of particle characteristics on deformation of particle reinforced metal matrix composites

Abstract The particle characteristics of 15% SiC particles reinforced metal matrix composites (MMC) made by powder metallurgy route were studied by using a statistical method. In the analysis, the approach for estimation of the characteristics of particles was presented. The study was carried out by using the mathematic software MATLAB to calculate the area and perimeter of each particle, in which the image processing technique was employed. Based on the calculations, the sizes and shape factors of each particle were investigated respectively. Additionally, the finite element model (FEM) was established on the basis of the actual microstructure. The contour plots of von Mises effective stress and strain in matrix and particles were presented in calculations for considering the influence of microstructure on the deformation behavior of MMC. Moreover, the contour maps of the maximum stress of particles and the maximum plastic strain of matrix in the vicinity of particles were introduced respectively.

Constitutive Equation and Processing Map for Hot Deformation of SiC Particles Reinforced Metal Matrix Composites

Flow behavior and microstructures of Al/15% SiCp were investigated by hot compression tests using Gleeble-1500 thermomechanical simulator at temperatures ranging from 440 to 500 °C with strain rates of 0.001-1.0 s−1. The high-temperature deformation behaviors of Al/15% SiCp were analyzed based on the true stress-true strain curves. The results show that the softening mechanism at low strain rate (0.001 s−1) is dynamic recovery, and at high strain rates (0.01, 0.1, and 1 s−1) is dynamic recrystallization (DRX). Based on these experimental data, a set of constitutive equations for Al/15% SiCp are described by the Zener-Hollomon parameter, and the coefficients of equations are found to be functions of strain. The constitutive equations reveal the dependence of flow stress on strains, strain rates, and temperatures. Furthermore, the mean error between the experimental and the calculated flow stress was computed. The result shows that the calculated results from constitutive equations are in good agreement with the experimental results. To demonstrate the potential workability of Al/15% SiCp, the processing map was established. The stable zones and the instability zones in processing map are identified and verified through micrographs. As a result, the optimum strain rates and temperatures for effective hot working of Al/15% SiCp were determined.

Effects of random particle dispersion and size on the indentation behavior of SiC particle reinforced metal matrix composites

This study investigates the effects of particle size, volume fraction, random dispersion and local concentration underneath a spherical indenter on the indentation response of particle reinforced metal matrix Al 1080/SiC composites. The ceramic particles in certain sizes and volume fractions were randomly distributed through the composite structure in order to achieve a similar structure to an actual microstructure as possible. The particle size and volume fraction affected considerably indentation depths and deformed indentation surface profiles. The indentation depth increases with increasing particle size, but decreases with increasing particle volume fraction. The experimental indentation depths were in agreement with numerical indentation depths in case the local particle concentration effect is considered. The local particle concentration plays an important role on the peak indentation depth. For small particle sizes and large volume fractions the random particle distribution affects the deformed surface profiles as well as the indentation depths. However, its effect is minor on residual stress and strain distributions rather than levels in the indentation region.

Effects of Random Particle Dispersion and Particle Volume Fraction on the Indentation Behavior of SiC Particle-Reinforced Metal-Matrix Composites

The present composite structure models assume that reinforcement particles are located in a repeated arrayed order through metal matrix. This study investigates the effect of both random particle distribution and particle volume fraction on the indentation behavior of Al 1080/SiC particle reinforced metal—matrix composites under a spherical indenter. The ceramic particles were distributed randomly in a certain particle volume fraction through aluminum matrix in order to achieve a similar structure to a real particulate composite structure as possible. The particle volume fraction strongly affects permanent indentation surface profiles and indentation depths. The indentation profile becomes smoother, and the peak indentation depth increases as the particle volume fraction decreases. The random particle distribution has a small effect on the peak indentation depth but affects strongly the permanent indentation profiles as well as the residual stress and strain fields in the indentation region. A small increase appears in the local particle concentration in the indentation region and is affected considerably by the random particle distribution. The hardness tests as well as the scanning electron microscopy micrographs of the indentation regions of specimens with different particle volume fractions are in good agreement with theoretical analysis.

Fatigue crack growth of SiC particle reinforced metal matrix composites

High stiffness ceramic reinforcement in a light alloy matrix can result in a substantial increase in fatigue resistance while maintaining cost at an acceptable level. The fatigue resistance of particulate metal matrix composites (MMCs) depends on a variety of factors, including reinforcement particle volume fraction, particle size, matrix microstructure and the presence of inclusions or defects that arise from processing. In particular, the crack growth behavior in particle reinforced MMCs is very much dependent on reinforcement characteristics, and on matrix microstructure. The goal of this work is to obtain a fundamental understanding of fatigue crack growth behavior and evolution of microstructure during fatigue. The ambient temperature fatigue behavior of 2080/SiC p composites was examined and compared to the behavior of the unreinforced alloy. In particular, the fatigue crack growth behavior of these materials as a function of R-ratio was quantified and modeled using the two-parameter (Δ K − K max) approach. The fatigue fracture behavior at different R-ratios was investigated and correlated with the fatigue response of the composite.

Dry wear properties of A356-SiC particle reinforced MMCs produced by two melting routes

SiC particle reinforced metal matrix composites (MMCs) were produced by a common liquid phase technique in two melting routes. In the first route, 5, 10, 15 and 20 vol% SiC reinforced A356-based MMCs were produced. In the second route, an Alcan A356 + 20 vol% SiC composite was diluted to obtain 5, 10, 15 and 20 vol% SiC MMCs. In both cases the average particle size was 12 μm. The composites that produced by two different routes were aimed to compare the dry wear resistance properties. A dry ball-on disk wear test was carried out for both groups of MMCs and their matrix materials. The tests were performed against a WC ball, 4.6 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40–60%. Sliding speed was chosen as 0.4 m/s and normal loads of 1, 2, 3 and 5 N were employed. The sliding distance was kept at 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. A complete wear microstructural characterization was carried out via scanning electron microscopy. The wear behaviors were recorded nearly similar for both groups of composites. Diluted samples showed lower friction coefficient values compared with the friction coefficient values of the vortex-produced composites. This was attributed poor bonding between matrix and particles in the vortex-produced composites associated with high porosities. But, in general, diluted Alcan composites showed slightly lower wear rate relationship with the particle volume percent and applied load when compared with vortex produced materials.

Determination of damage parameter in particle reinforced metal matrix composite by ultrasonic method

Ultrasonic technique is well known as a powerful tool for characterization of materials. It is typically used to determine the elastic constants of material but rarely to measure the damage parameter of materials [1, 2]. Particle reinforced metal matrix composites (PMMC) are excellent candidates for structural components in the aerospace and automotive industries due to their highly specific modulus, strength, and thermal stability [3]. It is necessary to study the properties of PMMC subjected to the combined loads of thermal and mechanical loads [4]. The damage and failure of SiC particle reinforced metal matrix composite have been studied induced by laser thermal shock and mechanical load [5]. It is found that when the combined loads of applied mechanical load σmax and laser energy density, EJ, were low, i.e., σmax and EJ were lower than the thresholds, there were no damage phenomena observed in the specimen. However, when the combined loads (σmax, EJ) became higher than the thresholds, damage phenomena were observed at the notch-tip of specimen by using scanning electron microscopy (SEM). It was observed that microscopic feature of damage was the voids in the matrix and interfacial debonding. Once the combined loads (σmax, EJ) were up to the high thresholds, the micro-cracks formed in the notched region would grow into macroscopic cracks. The fracture of the reinforcement particle was the dominant damage mechanism for macro-crack propagation. The reinforcements were broken by cracks perpendicular to the loading axis, and the fraction of broken reinforcements increased near the crack tip zone. It is very interesting that although the particles were broken near the macro-crack tip region, there was no damage in the matrix and at the particle/matrix interfaces. In this letter, the damage parameters of PMMC induced by laser thermal shock and mechanical load were quantitatively measured by ultrasonic technique. In order to study quantitatively the damage level, the damage parameter ω is defined as follows [6, 7],

Thermal failure mechanism and failure threshold of SiC particle reinforced metal matrix composites induced by laser beam

The failure of particulate-reinforced metal matrix composites (MMCs) induced by laser beam thermal shock is experimentally and theoretically studied. It is found that the initial crack occurs in the notched-tip region, wherein the initial crack is induced by void nucleation, growth and subsequent coalescence in the matrix materials or interface separation. However, crack propagation occurs by fracture of the SiC particle and it is much different from the crack initiation mechanism. The damage threshold and complete failure threshold can be described by a plane of applied mechanical load σ max, and laser beam energy density E J. A theoretical model is proposed to explain the damage/failure mechanism and to calculate the damage threshold and complete failure threshold. This model is based on the idea of stress transfer between a reinforced-particle and the matrix, as well as the calculation of the applied mechanical stress intensity factor and local thermal stress intensity factor. In order to check the validity of the theoretical model, the finite element simulations are carried out for the temperature field induced by laser heating, the stress fields induced by the combined laser heating and applied mechanical tensile load. Both the theoretical model and the finite element simulation can explain the experimental phenomenon. The theoretical model can predict the damage threshold and failure threshold. The failure of MMCs induced by laser thermal shock and applied mechanical load is non-linear.

Comparison of the mechanical properties of A356-SiC particle-reinforced metal matrix composites produced by two melting routes

SiC particle-reinforced metal matrix composites (MMCs) were produced by a common liquid-phase technique in two different melting routes. In the first route, 5, 10, 15 and 20 vol % SiC-reinforced A356-based MMCs were produced. In the second route, an Alcan A356 + 20 vol % SiC composite billet was diluted to obtain 5, 10, 15 and 20 vol % SiC-reinforced MMCs. In both cases the average particle size was 12 μ. The microstructural and mechanical property relationships of these composites were investigated. Vortex-produced MMCs showed a fairly good particle distribution accompanied by approximately 5-8 vol % porosity. Diluted Alcan composites produced excellent particle distribution and finer eutectic silicon crystals. Compressive and tensile properties were compared between vortex-produced and diluted composites. The results showed that diluted MMCs showed better properties compared with composites produced by the vortex method. Both composite groups were subjected to a T6 ageing heat treatment. The rate of increase in the yield, and tensile and compressive strength values were always higher in the as-cast materials than in T6 heat-treated composites with increasing SiC particle content. This difference was attributed to accelerated nucleation of precipitation and, therefore, overageing caused by ceramic particles. SEM investigations on the fracture surfaces showed that good particle bonding existed in the diluted composites.

Influence of processing parameters during disintegrated melt deposition processing on near net shape synthesis of aluminium based metal matrix composites

This paper addresses the influence of processing parameters on the near net shape synthesis of Al–SiC particle reinforced metal matrix composites by the disintegrated melt deposition technique. The processing parameters that were investigated include stirring speed during reinforcement addition, holding and stirring times following reinforcement addition, and total flight distance. The effect of the weight fraction of SiC incorporated was also studied. Maximum incorporation of the reinforcement was achieved by dispersing SiC particles in liquid aluminium with an impeller at a stirring speed of 500 rev min-1. Composite porosity levels were minimised for holding and stirring times following SiC addition of 15 and 5 min, respectively, and for a total flight distance of 450 mm. Composite porosity levels were increased with increasing weight fractions of SiC incorporated. The results obtained clearly demonstrate the dependence of composite porosity levels on weight fraction of reinforcement incorporated, total flight distance, and holding and stirring times following addition of SiC particles, and reinforcement incorporation on stirring speed.

PARABOLIC CURVED CRACK FRONTS IN FRACTURE TOUGHNESS SPECIMENS OF PARTICULATE REINFORCED ALUMINIUM ALLOY METAL MATRIX COMPOSITES

AbstractCrack front shapes in relatively thick fracture toughness specimens of Sic particulate reinforced metal matrix composites have been analysed. They were found to have a common shape, that of a parabola. This shape is thought to arise as a result of a distribution of residual stress across the test‐piece. A simple analysis is used to derive an expression for an effective crack length which can be used to calculate KIC values in specimens in which the crack fronts are excessively curved and do not meet relevant criteria for curvature in current standards for toughness testing of metallic materials.