Microstructures, Mechanical Properties, and Wear Resistances of Thixoextruded SiC_p/WE43 Magnesium Matrix Composites

Abstract

Near-net shaping of Mg-RE alloy matrix composites has received increasing attention. In this work, stir casting followed by extrusion was adopted to fabricate Mg-RE alloy (WE43) matrix composites reinforced by micron-sized SiC particles. The microstructural evolutions of SiC_p/WE43 composites partially remelted from as-cast and extruded states were studied. Furthermore, the thixoformability of SiC_p/WE43 composites in different states was evaluated by thixoextruding a type of double-cup component. The microstructures of as-cast SiC_p/WE43 composites were optimized under the comprehensive effects of SiC particles and RE elements. The SiC_p/WE43 composite was fully recrystallized during hot extrusion, and the α-Mg matrix consisted of fine equiaxed grains. Although the as-cast SiC_p/WE43 composite consisted of satisfactory structures and can be successfully thixoextruded into the final component with good surface quality and no evidence of internal defects, the microstructures, Vickers hardness, tensile mechanical properties, and wear resistance were still inferior to those of the component thixoextruded from extruded composite. Moreover, the thixoextrusion process was analyzed schematically, and an ideal thixoforming process that should contain two stages was proposed.