Effect of SiC nanoparticles addition on the microstructures and mechanical properties of ECAPed Mg9Al–1Si alloy

Abstract

This study investigated the effects of 1 wt% SiC nanoparticles addition on the microstructures and mechanical properties of Mg9Al–1Si (wt%) alloy subjected to equal channel angular pressing (ECAP). Results showed that addition of SiC nanoparticles could refine matrix grain, Mg₁₇Al₁₂ and Mg₂Si phase of as-cast alloy, but the Mg₁₇Al₁₂ phase still exhibited network structure and the morphology of Mg₂Si phase was still Chinese-script type. During the ECAP process, network Mg₁₇Al₁₂ and Chinese-script shaped Mg₂Si phases were partially broken down into fine particles (∼10 µm) and much finer particles (∼2 µm) respectively. In particular, these Mg₁₇Al₁₂ and Mg₂Si particles were uniform distribution in ECAPed Mg9Al–1Si–1SiC composite. The well-distributed particles and the existence of SiC nanoparticles could promote the formation of fine DRXed grains through enhanced grain boundary pinning. During tensile testing at room temperature, ECAPed Mg9Al–1Si–1SiC composite exhibit optimal mechanical properties, the ultimate tensile strength and elongation to failure were reached to 255 MPa and 7.9%, respectively. Furthermore, at elevated temperature of 150 °C, the tensile strength and elongation to failure were considerably increased compared to an ECAPed, SiC-free Mg9Al–1Si alloy.