Mechanical Behavior Of SiC/Al Metal Matrix Composites Considering Thermal Residual Stress

The manufacture of Particle Reinforced Metal Matrix Composites (PRMMC) is relatively simple and this kind of composites possesses the following advantages: low cost, secondary process, isotropy, wearable and so on. SiC particle reinforced aluminum alloy is a kind of special metal matrix composites with enhanced stiffness, strength, wear resistance, antioxidant ability and heat-resistance. At present, SiC/Al metal matrix is considered to be the most wide-used composites in the future.PRMMC's properties improve with increased volume fractions of reinforcement; however, the ductility decreases significantly because of local plastic deformation, which restricts its application in engineering. So it's necessary to do some research work about the micro-mechanism damage mechanical behavior of SiC/Al composites, the purpose is to establish the link between material's microstructure and the damage behavior. SiC/Al composite is produced through mixing the fine SiC particles into the aluminum melt. Because of the difference in thermal expansion coefficients between SiC inclusion and Al matrix, the temperature drop that occurs during cooling process will result in residual thermal stress/strain. Such a kind of thermal residual stress field will influence the principal micro-damage behavior of composites: interface debonding, cracking of particles and void nucleation, furthermore, the thermal residual stress field will influence ductility and other macro mechanical behavior. Different from the research work before, considering the thermal and mechanical constants such as Youngs modulus, Possion, specific heat and heat conductivity are all functions of temperature, the paper does some research work through unit cell approach using finite element method. Taking volume fraction and aspect ratio as parameters, the influence of various particle shape and size on the thermal residual stress field and micro mechanical behavior is researched through axisymmetric models, the results are compared with analytical result. Because axisymmetric model is limited in considering particle geometry, particles clustering effect is investigated through both axisymmetric and 3D models. Surface-centered-cubic and body-centered-cubic models are used to study the various thermal residual stress fields, the results are more valuable for interface stress design in composites manufacture. Based on the methods and results above, fracture ductility and Bauschinger effect influenced by thermal residual stress field are studied. This paper draws a series of conclusions, which are in accordance with some experiment results before. The results are also valuable for particle reinforced metal matrix composites manufacture and application.