Rheo-Die-Casting of Al-Si-Mg Alloy and Al-Si-Mg/ SiC_p Composites: Microstructure and Wear Behavior

Abstract

In this paper, Rheo-Die Cast (RDC) Al-Si alloy with 7.5 wt % Si and 0.3 wt %Mg and Metal Matrix Composites (MMC’s) of RDC Al-Si composites with 5 to 20 vol. % of SiC_p were produced by an in-house fabricated RDC machine. Microstructure and wear behavior of both RDC alloy and composites were investigated. Results indicated that the RDC samples have significantly refined microstructure with fine and uniform non-dendritic grains resulting increased hardness and enhanced wear resistance. Wear resistance is three times higher for sample with 20% SiC_p than those without SiC_p additions. Surfaces of wear test samples were investigated by SEM to study the effect of both grain structure and SiC_p particulates on the wear mechanism. It was also observed that reinforced RDC samples showed improved hardness and wear resistance due to the presence of SiC_p in the matrix of non-dendritic grains, obtained without modification treatment.

Keywords:
Aluminum alloy; composites; semisolid processing; microstructure; mechanical properties