稀土Ce对铸态AlCuMgAg合金耐热性能的影响

Effects of Minor Ce Addition on the Heat Resistance of As-cast AlCuMgAg Alloy

采用拉伸测试与透射电镜 (TEM) ,研究了稀土Ce对铸态Al 5 .3Cu 0 .8Mg 0 .6Ag(质量分数 )合金的组织和耐热性能影响。结果表明 ,添加质量分数为 0 .2 0 %～ 0 .45 %的Ce ,在室温到 3 0 0℃ ,铸态合金的室温抗拉强度和高温耐热性能得到了提高。金相显示 ,稀土Ce的添加能明显细化铸态合金的晶粒 ,减少晶界上Cu的偏析。透射电镜分析表明 ,合金中的主要强化相为Ω相 ;添加微量Ce能细化合金中的强化相 ,提高该相的析出密度。同时研究也表明 ,当合金中同时添加微量Ce和Ti时 ,铸态合金中形成了一种AlxTi6Ce3 Cu的大块稀土化合物相 ,这种化合物相严重降低了合金的拉伸性能。

Effects of various minor Ce additions on microstructure and heat resistance of as cast Al 5.3Cu 0.8Mg 0.6Ag alloy have been investigated by tensile testing and TEM (transmission electron microscopy).The results showed that the tensile strength at room temperature and heat resistance at high temperature of the as cast alloy can be improved by adding 0.20%～0.45% Ce at room temperature to 300 ℃.It is found that the Ce could refine the grain size of the alloy obviously and reduce Cu segregation in grain boundary.TEM indicated that minor Ce can refine strengthening Ω phase with increase in its precipitated density.A bulk Al x Ti 6Ce 3Cu compound appears in the as cast alloy which deteriorated sharply the tensile strength with adding both minor 0.2%Ce and 0.25%Ti.