Microstructure and mechanical properties of die-cast AZ91D magnesium alloy by Pr additions

来源期刊：中国有色金属学报(英文版)2010年增刊第2期

论文作者：崔晓鹏 刘海峰 孟健 张德平

文章页码：435 - 438

Key words：praseodymium; magnesium alloy; microstructure; mechanical properties

Abstract: Mg-9Al-xPr (x=0.4, 0.8 and 1.2, mass fraction, %) magnesium alloys were prepared by high-pressure die-casting technique. The effects of Pr on the microstructures of die-cast Mg-9Al based alloy were investigated by XRD and SEM. Needle-like Al₁₁Pr₃ phase and polygon Al₆Mn₆Pr phase are found in the microstructure. With 0.4% Pr addition, fine needle-like Al₁₁Pr₃ phase and a small amount of polygon Al₆Mn₆Pr phase near the grain boundary are found in the microstructure. Increasing Pr addition to 0.8%, lots of coarse needle-like Al₁₁Pr₃ phase within grain and polygon Al₆Mn₆Pr phase on grain boundary are observed. Further increasing Pr addition, the size of needle-like Al₁₁Pr₃ phase decreases, while the size of polygon Al₆Mn₆Pr relatively increases. The mass fraction of Pr at around 0.8% is considered to be suitable to obtain the optimal mechanical properties. The optimal mechanical properties are mainly resulted from grain boundary strengthening obtained by precipitates and solid solution.