Structure–property correlation in discontinuously reinforced aluminium matrix composites as a function of relative particle size ratio

Metal matrix composites made by a powder metallurgy route often exhibit clustering of the reinforcements due to geometrical reasons. The clustering tendency was studied in 2124 Al/30 v/o SiCp composites as a function of relative particle size ratio between the matrix and reinforcement particles. Dry blended composite powders, with different RPS ratios, were vacuum hot-pressed and microstructures were examined to assess the uniformity of the microstructure by measuring the local area fraction of the constituents. It was found that a decrease in RPS ratio resulted in an increase in strength as well as ductility, as a result of improved distribution of the SiCp. The improved response to the homogenisation treatment, observed in the composite with lower RPS ratio, is attributed to the smaller diffusion path length for the alloying element.