RE元素Y和Nd对Mg-6Al合金显微组织的影响

Effects of Y, Nd RE-Element on the Microstructure of Mg-6Al Alloy

研究了RE元素Y和Nd元素对Mg 6Al镁合金在铸态和固溶热处理状态下显微组织的影响。金相显微镜、扫描电镜及电子探针分析结果表明 ,Y和Nd稀土元素均有促进Mg 6Al合金铸态组织晶粒细化的作用 ,添加质量分数为 0 .5 %的Y元素可使合金的晶粒尺寸由Mg 6Al合金的 10 2 .0 0 μm细化至 76.92 μm ,加入质量分数为 1%的Nd后合金晶粒尺寸为65 .79μm ,而且Y和Nd在复合加入时 ,细化效果更为显著 ,晶粒尺寸为 5 7.47μm。Y和Nd与合金中的铝元素形成热稳定性较高的块状YAl2 相和条状NdAl2 相 ,两者在α Mg晶粒内和晶界均有分布。

Effects of Y and Nd on the as-cast and solid solution treated microstructure of Mg-6Al alloy were investigated. It was showed by OM, SEM, EMPA that both Y and Nd can promote the refinement of as-cast microstructure of Mg-6Al alloy. The grain size of 76.92 μm with 0.5% Y addition in modified Mg-6Al alloy was substituted for that of 102 μm in base alloy while it decreased to 65.79 μm with 1%Nd addition. Furthermore, the grain size with both Y and Nd addition reduced to 57.47 μm. The Y and Nd-RE can be combined with Al in base alloy to form block-like YAl 2 phase and rod-like NdAl 3 phase with high thermo-stability respectively. The Mg 17Al 12 phase was dissolved in α(Mg) matrix during solid solution treatment while the new phases were not dissolved in the α(Mg) matrix due to its high thermostability.