The Fabrication of Aluminium Composites via Stir-Mixed and Particulate-Injection Casting

The fabrications of aluminium composites of 10 and 15 wt% SiC_p additions were investigated in this research in search of potentially cheaper processing alternatives. Mixing of SiC_p into aluminium 356 alloy melt was employed via (i) stir mixed casting and (ii) particulate injection casting using a modified flux injection degassing technique. Fabrication parameters such as SiC_p additions, mixing speed, mixing and casting temperatures were monitored to evaluate their effects on microstructure and properties. Results showed that stir-mixed casting provided optimum density and hardness at 10 wt% SiC_p addition. Porosity was present along with SiC_p clusters, resulting in property degradation. Particulate-injection castings of 15 wt% SiC_p and 680 °C casting temperature offered superior density and hardness values, due to relieves of gas porosity and SiC_p sedimentation via degassing, giving good potential for low-cost composite production.