Influence of Hot Extrusion on the Microstructure, Tensile and Wear Properties of Mg–5Sb–xSiC Hybrid Composites

Abstract

The structure, hardness, tensile and wear behavior of Mg–5Sb–xSiC hybrid composites experimented where the amount of SiC particles were 1, 3, and 5 wt% SiCp before and after applying hot extrusion process. Micron size SiC particles were added to Mg–5Sb alloy via stir casting technique to form both Mg3Sb2 and SiC particles in the as-cast microstructures. Although SiC addition reduced the grain size of the Mg–5%Sb in-situ metal matrix composite (MMC), no improvement was observed on ultimate tensile strength (UTS) and the ductility (EL.%) in the as-cast state. The use of the extrusion process led to a remarkable fracturing of Mg3Sb2 intermetallic along the extrusion direction, grain refinement, and reduction in the size of SiC clusters. The optimal amount of SiC was found to be 3 wt%, which reduced the grain size from ~ 827 to ~ 4 µm and promoted the UTS amounts from 120 to 244 MPa for as-cast and hot extruded composites. Besides, the enhancement of yield strength of extruded MMCs was rationalized depending on the grain size compared to the as-cast condition. The fractography of the as-cast composites revealed more cleavage planes in contrast with hot extruded composites, which proved much more dimples. It was also found that the use of hard SiC particles in hybrid composite improved wear properties just in the extruded state. According to observations, in various sliding test conditions, the abrasive, oxidation and delamination are mostly operated in combination.