MICROSTRUCTURE REFINEMENT OF Mg-Al-Zn-Si ALLOYS
YUAN Guangyin, LIU Manping, WANG Qudong, ZHU Yanping, DING WenjiangState Key Laboratory of Metal Matrix Composites, Shanghai Jiaotong University, Shanghai 200030
Magnesium alloys containing Mg2Si particles, as a promising cheap heat-resistant magnesium alloy for automobile engine applications, are attracting more and more attention of both material scientists and design engineers. Refinement of the Chinese script Mg2Si particle is a key for using this alloy in sand casting or permanent mould casting. The refinement effect of antimony (Sb) on the microstructure was investigated. It shows Sb addition promotes the formation of fine polygonal type Mg2Si particles by providing the nucleation sites. Moreover, the grain sizes of Sb modified Mg-Al-Zn-Si alloy is much finer than that of base alloy. The improved microstructure of the modified alloy results in the large improvement in toughness and tensile properties at both ambient and elevated temperature of 150℃ as compared to the base alloy.