Fabrication and tensile properties SiCp/AZ91 Mg composites by hot

The tensile properties and microstructural evolution of hot-extruded SiCp/AZ91 Mg matrix composites have been investigated in terms of extrusion parameters such as extrusion ratio and SiC particulate size. Also, the effect of SiC particulate on the grain size of the matrix in the composites was studied using Hall-Fetch equation. The AZ91 Mg alloy powders, which were prepared by wet attrition milling from Mg machined chips, were consolidated with hot press and then extruded at elevated temperature. The microstructures of both composites and Mg alloy shows that they have fine equiaxed grains due to the dynamic recrystallization during hot extrusion. The tensile strength of the both composites and Mg alloys was increased with increasing extrusion ratio, and the strength of the composites were higher than that of the Mg alloy. From analysis of the microstructures and the mechanical properties combined with examination of the Hall-Fetch relationship, the refinement of the matrix was primarily responsible for the improvement in the yield strength of the composites. The grain growth of the matrix was inhibited by the introduction of the SiC particulate.