Tensile properties and strengthening mechanisms of SiC_p-reinforced aluminum matrix composites as a function of relative particle size ratio

Metal matrix composites manufactured by the powder metallurgy route often exhibit different tensile strength due to particle geometrical reasons. The tensile strength tendency was studied in 2024 Al/30% SiCp composites as a function of relative particle size (RPS) ratio between the matrix and reinforcement particles. Dry blended composite powders, with different RPS ratios, were hot-pressed in vacuum, their microstructures were observed, and their tensile properties were measured. It was found that a decrease in RPS ratio resulted in a decrease in tensile strength, as a result of improved distribution of the SiCp. Despite their low density and heterogeneous distribution, 3-μm SiCp-reinforced composites had maximum tensile strength. The main reasons were due to the few fracture for small SiCpand the strengthening of the matrix microstructure from small particle effects. Solution treatment plus aging of the composites with the RPS ratio of 10:3 resulted in a significant improvement (42%) in strength due to the smaller diffusion path length for the alloying element.