Development and mechanical characterization of LM6/Al2O3/SiC/Graphite metal matrix composites using stir casting

Abstract

ABSTRACT In the present study, three reinforcements viz. graphite, SiC and Al2O3 were added in LM6 matrix to evaluate their strengthening efficiency. Stir casting technique was utilised for fabrication of composites, where the amount of reinforcements varied from 1.0 wt.% to 3.0 wt.%. Hardness and tensile strength was performed to evaluate the mechanical properties and optical microscopy was utilised to analyse the microstructure of the prepared composites. It was observed that the tensile strength and hardness increased linearly, irrespective of the reinforcement type and content. However, graphite reinforced composites exhibited best mechanical properties followed by SiC and Al2O3 reinforced composites. From the optical microscopy images, it was clearly observed that as the concentration of reinforcement increased, the tendency to form agglomerates also increased eventually resulting in porosities. However, composites containing large amount of reinforcements still displayed highest values of tensile strength and hardness. This might be attributed to the fact that the detrimental effect of porosities was negligible as compared to the strengthening effect exerted by the reinforcements.