The effect of matrix to reinforcement particle size ratio (PSR) on the microstructure and mechanical properties of a P/M processed AlCuMn/SiCp MMC

Matrix to reinforcement particle size ratio (PSR) is the main factor governing the homogeneity of the reinforcement particle distribution in composites manufactured by the powder metallurgy route. To improve the homogeneity of the distribution, reinforcements with larger average particle size should be used. At the same time, increasing the reinforcement particle size leads to worsening of the mechanical properties due to lower work hardening and higher damage accumulation rates. It is therefore important to optimize the microstructure somewhere in between a smaller reinforcement particle size and a more homogeneous spatial distribution. The effect of PSR on the reinforcement spatial distribution, fabricability, and resulting mechanical properties of a P/M processed AlCuMn/SiC/15p composite was investigated. It was shown that increasing the PSR results in a less-uniform reinforcement distribution, which in turn leads to a decrease in the material fabricability and a general worsening of the mechanical properties. A close to linear dependence of the mechanical properties (yield stress, UTS, elongation before fracture, Young’s modulus) on PSR was found. Tensile elongation shows the highest sensitivity to the worsening of the homogeneity of the reinforcement spatial distribution caused by increasing the PSR. The effect of microstructural homogeneity on the relative change of mechanical properties does not seem to depend on matrix alloy plasticity.