Grain Refinement of AZ61/SiCp Magnesium Matrix Composites for Tubes Extruded by Hot Extrusion Processes

摘要

Magnesium (Mg) alloys are gaining more recognition as a lightest structural material for light-weight applications, due to their low density and high stiffhess-to-weight ratio. Nevertheless, their ductility is still not good for further metal forming and their strength is not large enough for real structure applications. The aim of this paper is to develop new magnesium metal matrix composites (Mg MMCs) reinforced with SiC particles by the stir-casting method for the hot extrusion processes to produce tubes. AZ61/SiCp MMCs' ingots reinforced with 1, 2, and 5 wt% SiC particles are fabricated by the melt-stirring technique. AZ61/SiCp MMCs' tubes are manufactured by hot extrusion using a specially designed die-set for obtaining uniform thickness distribution tubes. Finally, the mechanical properties of the reinforced AZ61/SiCp MMCs and Mg alloy AZ61 tubes are compared with those of the billets to manifest the advantages of extrusion processes and addition of SiC particles. The microstructures of the billet and extruded tubes are also observed. Obvious grain size refinement both by addition of particles and extrusion process are discovered.