Production of Al-Si-SiCp cast composites by injection of low-energy ball-milled Al-SiCp powder into the melt

Abstract

Al-7wt%Si-10wt%SiCp composite with uniformly distributed reinforcement particles with the average size of about 3 microns was produced by a special compocasting method in which the reinforcement was injected into the melt in the form of particulate Al-SiCp composite powder instead of SiCp. The effects of the reinforcement addition form, the solid fraction of primary alpha-aluminum particles at pouring, and stirring speed on the incorporation of reinforcement particles into the matrix were investigated. Injection of particulate Al-SiCp composite led to improved incorporation and dispersion and reduced size of SiCp. Casting from the semisolid state significantly improved the incorporation of SiCp into the matrix. The optimal solid fraction of primary alpha-aluminum particles to achieve a reasonable combination of reinforcement incorporation and fluidity of the composite slurry was recognized to be about 0.1. The incorporation of SiCp was improved by increasing the stirring speed up to 500 rpm and then gradually decreased.