Mg-xGd-1Er-0.5Zr合金的铸造流动性研究

Casting Fluidity of Mg-xGd-1Er-0.5Zr Alloy

采用螺旋试样法研究了Mg-xGd-1Er-0.5Zr(x=8、10、12,质量分数/%)合金的铸造流动性能。结合XRD及热分析法,研究了合金凝固过程中的相析出行为,分析了微观组织变化。结果表明,Gd含量的增加会抑制α-Mg的形核析出,使液相线温度降低,合金熔体自由流动时间增加,使凝固温度区间变窄,能有效改善合金的流动性能。此外,Gd含量的增加使Mg-xGd-1Er-0.5Zr合金的晶粒尺寸下降,流动长度增加,这是由于细化晶粒提高了合金流动时液流前端枝晶搭接时的固相率,延迟了枝晶的搭接。

The casting fluidity of Mg-xGd-1 Er-0.5 Zr(x=8,10,12,in mass fraction)alloy was investigated by spiral specimen method.The phase precipitation and microstructure of the alloy during solidification were analyzed by XRD and thermal analysis.The results show that with the increase in Gd content,the nucleation and segregation ofα-Mg can be inhibited,and the liquidus is decreased and the free flow time of the alloy melt is increased,reducing the solidification temperature range and improving the fluidity of the alloy.In addition,the grain size of Mg-xGd-1 Er-0.5 Zr alloy is decreased and the flow length is increased with increasing in the Gd content,which is attributed to grain refinement that improves the solid phase ratio of dendrite lapping at the front of liquid flow and delays the dendrite lapping.