Effect of ECAP ‘equal channel angular pressing’ on Al-SiCp composite

Abstract

Stir casting method was used to produce conventional metal matrix composites (MMC) with fairly homogenous dispersion of reinforcement material. Al-6061 and silicon carbide particles (15 μm) were selected as matrix and reinforcement materials respectively. The composites material were adjusted to contain 5% and 7.5% volume fraction of SiC. The matrix was first completely melt and kept for homogenizing at 750ºC. Then SiC powder preheated to 800 ᵒC was added during stirring action and when the vortex appeared. 1%wt of Mg was added to molten metal to improve wettability between the matrix and reinforcement. The melt mixture was poured into a metallic mold. The as-cast composites were processed by Equal Channel Angular Pressing (ECAP) route Bc at 300ᵒC. The microstructure and mechanical properties were studied for as-cast and ECAPed specimen. Results showed that as-cast Al-SiC composites can be successfully fabricated using stir casting technique as the simplest and the cheapest method. The maximum porosity and agglomeration level for as-cast composites reached 2.75% and 0.35%, respectively, for 5%SiC while that for 7.5% SiC was 3.93% and 0.8%. Adding the SiC by 5% in the matrix increased the strength, while it decreased for 7.5%SiC. The hardness continued to increase by increasing the SiC content for all compositions.