Mechanical properties of as-cast and heat-treated ZA-27/silicon carbide particulate composites

Abstract

This paper describes a study of the mechanical properties of as-cast and heat-treated ZA-27 zinc-aluminium alloy particulate composites containing silicon carbide (SiC) particles of size 100-150 μm and of contents ranging from 0% to 5% by weight. The 'vortex method' of production was employed in which the SiC particles were poured into the vortex created by stirring the molten metal by means of a mechanical agitator. Subsequent homogenizing heat treatment was performed at 320°C for durations of 1, 2, 3 and 4 hours, respectively. The results of this study revealed that as SiC composition was increased, there were significant increases in the ultimate tensile strenght (UTS) and hardness of the composite, accompanied by reductions in its ductility and impact strength. Heat treatment was found to improve significantly the ductility and impact strength of the composite, but cause reductions in its UTS and hardness. An attempt is made in the paper to provide explanations for these phenomena. © 1996.