EFFECTS OF Bi ADDITION ON SOLIDIFICATION BEHAVIOR AND MICROSTRUCTURE OF AZ80 MAGNESIUM ALLOY
WANG Yaxiao, FU Junwei, WANG Jing, LUO Tianjiao, DONG Xuguang, YANG Yuansheng
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016
Cite this article:
WANG Yaxiao FU Junwei WANG Jing LUO Tianjiao DONG Xuguang YANG Yuansheng. EFFECTS OF Bi ADDITION ON SOLIDIFICATION BEHAVIOR AND MICROSTRUCTURE OF AZ80 MAGNESIUM ALLOY. Acta Metall Sin, 2011, 47(4): 410-416.
Abstract The solidification behavior and as--cast microstructure in AZ80-Bi magnesium alloy were analysed by OM, SEM, XRD and DSC. Meanwhile, the evolution of the solidification microstructure of AZ80-2%Bi alloy was studied by heating-quenching experiments. The results show that the as-cast microstructure of AZ80-2%Bi consists of primary α-Mg matrix, divorced eutectic β-Mg17Al12 phase and Mg3Bi2 phase. The Mg3Bi2 phase exists in the flake-like and granule-like morphologies. With 2.0%Bi addition, the solidification procedure of AZ80 magnesium alloy is changed. The ternary eutectic transformation L→α-Mg+β-Mg17Al12+Mg3Bi2 (at 435 ℃) takes place during solidification of AZ80-2%Bi alloy instead of the binary eutectic transformation L→α-Mg+β-Mg17Al12 (at 437 ℃) in AZ80 alloy. Comparing with AZ80 alloy, the nucleating temperature of primary $\alpha$--Mg in AZ80--2\%Bi alloy is decreased from 568.8 ℃ to 562.6 ℃, and the eutectic temperature is also decreased from\linebreak 424.2 ℃ to 421.1 ℃.