Development and Property Evaluation of Aluminum-Alloy Reinforced with Nano-ZrO ₂ Metal Matrix Composites (NMMCs) for Automotive Applications

In the present research nano- ZrO₂ particulates were dispersed in aluminum alloy (LM 13) by melt deposition technique followed by hot extrusion. The size of the particles dispersed varies from 50–80 nm and amount of addition varies from 3 to 15 wt.% in steps of 3%. Microstructural studies of the NMMCs developed indicate that there is uniform distribution of the reinforcement in the matrix alloy with significant grain refinement and retention of residual porosity. Mechanical properties reveal that presence of nano- ZrO₂ particulates has improved significantly the strength and hardness with slight reduction in ductility as compared against the matrix alloy. Fractography of the specimens showed that the fracture behavior of matrix alloy (FCC structure) has changed from ductile intergranular mode to cleavage mode of fracture because of presence of ZrO₂ reinforcement. Results of the thermal and electrical tests on the composites developed indicate that, thermal conductivity and electrical resistance both decreased with increase in reinforcement content.