Compressive deformation behaviour of coarse SiC particle reinforced composite: Effect of age-hardening and SiC content

Compressive deformation of 2014 Al-alloy-SiCp composite has been compared with that of 2014 Al-alloy in as-cast and peak aged condition. In as-cast condition, the strength, elastic modulus and strain-hardening exponent of the alloy were improved significantly at the expense of its ductility due to reinforcement of SiC particles. After peak aging, the strength of individual material increased, but the elastic modulus and work hardening rate remained almost unchanged. It was interestingly noted that in peak aged condition composites exhibited less strength as compared to that of the alloy. However, the strength, the elastic modulus and the strain-hardening exponent of the composite increased with increase in SiC content irrespective of the processing condition. These have been explained in the perspective of matrix flow and crack propagation depending on interface characteristics, matrix strength and particle shearing. In cast condition, the matrix strength is low enough and the particles are quite stronger than the as-cast matrix. As a result, the particles are capable to resist the flow of the matrix, and the crack propagates primarily through the interdendritic region of the matrix. But in heat-treated condition, the matrix strength increased significantly. It results in intensifying the stress intensity above a critical value at the sharp tip of the flaws within the particles causing particle failure prior to the matrix failure.