Abstract:SiC particles reinforced AZ91 Mg matrix composites (SiC_p/AZ91) with SiC volume fractions of 5%, 10% and 15% were fabricated by stir casting. After T4 treatment, these composites were extruded at 350 °C with an extrusion ratio of 12:1. In the as-cast composite, particles segregated at a microscopic scale within the intergranular regions. Hot extrusion almost eliminated this particle aggregation and improved the particle distribution of the composites. In addition, extrusion refined the grains of matrix. The results show that hot extrusion significantly improves the mechanical properties of the composites. In the as-extruded composite, with the increase of SiC_p contents, the grain size of the extruded composites decreases, the strength and elastic modulus increase but the elongation decreases.

Key words: extrusion; Mg matrix composites; SiC_p; AZ91 magnesium alloy; volume fraction