添加微量Y对ZL205A合金组织和性能的影响

Effect of Trace Y Addition on Microstructure and Mechanical Properties of ZL205A Alloy

摘要:

采用OM、SEM和XRD研究了添加微量稀土元素Y对ZL205A合金的流动性及T6热处理前后的微观组织和力学性能的影响，并检测了合金的流动性。结果表明，当Y质量分数达到0.2% 和0.3% 时，合金的晶粒细化效果相对较好，随着Y含量的增加，θ相从沿着晶界的网状分布逐渐向局部团聚，合金的抗拉强度和屈服强度降低; 微量Y会使ZL205A合金的流动性降低；Y质量分数为0.3% 的ZL205A合金在 T6处理后，合金的抗拉强度和延伸率均大幅度提高；热处理能够降低合金中的成分偏析并能够改善材料的组织形态，促使合金具有相对较好的综合力学性能；添加微量Y以后，晶界上的难熔化合物AlCuY促使晶粒内部的θ相数量减少，是造成合金力学性能降低的重要原因。

Abstract:

The effect of the rare earth Y addition on the microstructure and mechanical properties of ZL205A alloy was studied by OM, SEM and XRD before and after heat treatment. The fluidity of the alloy was also tested. Results show that when the content of Y is 0.2wt% and 0.3wt%, the grains refinement effect is better. With the increase of Y, the θ phase distribution transforms from reticular into dendritic, and the yield strength and tensile strength decrease. Trace Y addition decreases the fluidity of ZL205A alloy. When the Y content is 0.3wt%, the tensile strength and the ductility increase significantly after T6 heat treatment. Heat treatment process can reduce the composition segregation of alloys and improve the microstructure, resulting in a better comprehensive mechanical performance. After adding a small amount of Y, the compound AlCuY, which has high melting point, low strength and is difficult to be melted, can decrease the amount of θ phase, which is an important reason to the declined mechanical properties.