微量Sc和Zr对Al-Mg合金铸态组织的晶粒细化作用

EFFECT OF TRACE Sc AND Zr ON GRAIN REFINEMENT OF AS CAST Al Mg ALLOYS

制备了Ａｌ５Ｍｇ、Ａｌ５Ｍｇ０．２Ｓｃ、Ａｌ５Ｍｇ０．１Ｚｒ和Ａｌ５Ｍｇ０．２Ｓｃ０．１Ｚｒ四种铸态合金，采用金相显微镜和扫描电镜观察分析了微量Ｓｃ和Ｚｒ对ＡｌＭｇ合金铸态组织的晶粒细化作用及其机理。结果发现，０２％的Ｓｃ并未使ＡｌＭｇ合金产生晶粒细化作用，而０２％的Ｓｃ与０１％的Ｚｒ复合添加则使ＡｌＭｇ合金产生了极其强烈的晶粒细化作用。这一作用的产生，是由于Ｓｃ、Ｚｒ与Ａｌ在合金熔体中生成了Ａｌ３Ｓｃ和Ａｌ３Ｚｒ复合粒子，这种粒子在合金凝固过程中。

Al 5Mg, Al 5Mg 0.2Sc, Al 5Mg 0.1Zr and Al 5Mg 0.2Sc 0.1Zr cast alloys have been prepared. The effect of trace Sc and Zr on grain refinement of Al 5Mg cast alloy was studied using optical microscopy and scanning electron microscopy with EDS. The results showed that adding 0.2%Sc and 0.1%Zr to Al 5Mg alloy leads to strong grain refinement but adding only 0.2%Sc to Al 5Mg alloy has no grain refinement phenomenon. This is because, during solidification, Al 3Sc/Al 3Zr composite particles were formed in the melt playing a role of the nuclei of imhomogenized crystallization.