中文摘要：

采用Mg-10Al-27Ca中间合金的方式在Mg-9Li合金中添加微量Ca及Al元素,利用磁悬浮熔炼和铜模吸铸的方法熔炼制备了Mg-9Li-0.5Ca-0.18Al合金,考察微量Ca添加对Mg-9Li双相合金组织与力学性能影响。结果表明,相比于常规用Mg-30Ca、纯Al的Ca、Al添加方式,以Mg-10Al-27Ca中间合金方式添加Ca、Al元素对Mg-9Li双相合金中α-Mg相的组织细化和均匀化效果更为显著,形成的Al2Ca颗粒分布也更为均匀弥散。经Mg-10Al-27Ca中间合金方式添加0.5 wt%Ca后,合金的屈服强度、抗拉强度较Mg-9Li合金分别提高75.8%、52.5%,伸长率仅下降7.6%,合金的断裂韧性得到提高。Mg-10Al-27Ca中间合金中形成的细小、分布均匀的Al2Ca颗粒对α-Mg相优良的异质形核作用是Mg-9Li-0.5Ca（Mg-10Al-27Ca）-0.18Al合金组织细化、力学性能提高的根本原因。

英文摘要：

Small amounts of Ca and Al elements were added into Mg-9Li alloy by Mg-10Al-27Ca master alloy and magnetic levitation melting as well as copper mold suction casting techniques were applied to prepare Mg-9Li-0.5Ca-0.18Al alloy. The effects of rare content of Ca addition on the properties of Mg-9Li alloy were studied. The results show that compared with Mg-30Ca and pure Al addition manner, Ca and AI additions by Mg-10Al-27Ca master alloy into Mg-9Li alloy produce a much finer and more homogeneous structure of α-Mg phase accompanying with more uniform and dispersed Al2Ca particles. The yield strength and tensile strength of the alloy after addition of 0.5 wt% Ca by Mg-10Al-27Ca master alloy manner increases by 75.8%, 52.5%, respectively, while the ductility in percent elongation slightly decreases by 7.6%, and hence, the toughness of the alloy is enhanced significantly. The excellent heterogeneous nucleation effect of the finer and uniformly distributed AI2Ca particles forming in Mg-10Al-27Ca master alloy on α-Mg phase contributes to the finer microstructure and higher mechanical property of Mg-9Li-0.5Ca（Mg- 10Al-27Ca）-0.18Al alloy.