Microstructure and mechanical properties of LPSC AZ91-Sb magnesium alloy

ABSTRACT Microstructures and mechanical properties of AZ91-Sb magnesium alloy fabricated by low-pressure shell casting (LPSC) process in different conditions were investigated. The as-cast alloy exhibited a good internal quality and denser structure. The microstructure of α-Mg phases displayed dendritic feature and fine isolated β-Mg17Al12 particles phases uniformly distributed in the matrix. After the solution treatment at 415°C for 12 h, almost β-Mg17Al12 phases dissolved into the matrix. After ageing treatment at 200°C for 14 h, the LPSC alloy attained the peak hardness with restrained age-hardening kinetics. The discontinuous precipitates initiated at the grain boundaries and then continuous precipitates occurred in the grain interior. The LPSC alloy exhibits higher mechanical properties in both as-cast and heat-treated alloys compared with the gravity casting (GC) process alloy.