Wear of semi-solid rheocast SiCp/Al metal matrix composites

Abstract

Rheocasting of plates in Al alloy 359 reinforced with SiC at 11%, 27% and 50% (volume fractions) exhibits the capability of the council for scientific and industrial research-rheocasting system (CSIR-RCS) in rheo-processing and high pressure die casting of SiC metal matrix composites. The metal matrix consisting of nearly spherical proeutectic a(Al) globules was produced. Spheroidization of fibrous eutectic silicon took place upon heat treatment of the as-cast metal matrix composites (MMCs). Hardness increases as the volume fractions of SiC increases. Wear rates of the MMCs in the F and T6 heat treatment conditions were assessed with a metallographic preparation machine. It is found that the 11% SiC MMC wear rate is higher on SiC abrasives compared with the 50% SiC MMC wear rate due to wear of the aluminum matrix. This trend is reversed on diamond abrasives due to pull-out of the irregular shaped composite particles. The 50% SiC MMC suffers from composite particle fracture porosity after high pressure die casting (HPDC)