The Wear Behavior of a Cast Al-20wt%Mg2Si Composite Thixoformed Via SIMA

Abstract

: Aluminum matrix composites are candidate materials for aerospace and automotive industries owing to their specific properties such as high elastic modulus (E), suitable strength and low wear rate. The effect of thixoforming process on the wear behavior of an Al-Mg 2 Si composite sample was studied in this paper. In thixoforming process, casting defects such as macrosegration, shrinkage and porosity are reduced significantly. These advantages are sufficient to attract further studies on thixoforming operation. Thermal analysis of the composite sample, as-cast microstructure, wear surface and subsurface area of the thixoformed alloy were investigated. Wear behavior of the specimens were examined using a pin-on-disk machine based on ASTM-G99, at the applied loads of 25, 50 and 75 N and the constant sliding velocity of 0.25m/s. The worn surfaces and subsurfaces were examined by scanning electron microscopy (SEM). The experimental results indicated that the thixoformed specimens exhibited superior wear resistance than the as-cast alloy. Moreover, the dominant wear mechanism is an adhesive wear followed by the formation of a mechanical mixed layer (MML). However, a severe wear regime occurs in the as cast specimens compared to the thixoformed counterparts.