中文摘要：

采用常规金属型铸造工艺和磁悬浮熔炼＋负压铜模吸铸工艺制备了Mg69.5Li26.8Gd2.5Zn1Zr0.2（a%）双相Mg-Li合金。利用光学显微镜、X射线衍射仪和力学性能试验机等对合金的显微组织及力学性能进行了系统的分析。结果表明,两种方法制备的合金在铸态下都出现了LPSO相。但是,磁悬浮熔炼＋负压铜模吸铸工艺比常规金属型铸造所产生的更大的冷却速度,使得合金各相的晶粒/颗粒尺寸显著减小、分布更为均匀弥散。LPSO相形貌从层片状为主的层片＋块状混合形态转变为块状、尺寸减小、体积分数明显增加,力学性能显著高于常规金属型铸造工艺制备的合金。

英文摘要：

Mg69.5Li26.8Gd2.5Zn1Zr0.2 （a%） dual-phase Mg-Li alloy was prepared by conventional metal mold casting and magnetic levitation melting coupled with negative suction casting with copper mould. The microstructures and mechanics properties of as-cast were investigated by means of optimal microscope （OM）, X-ray diffraction （XRD） and electronic universal material test machine. The results indicated that LPSO phase was formed by both two methods. However, Compared to the conventional metal mold casting, the fast cooling rate induced by magnetic levitation melting coupled with negative suction casting with copper mould makes the grain/particle size of each phase in the alloy decreases, and the distribution more uniform. Meaningwhile, the morphology of LPSO phase is varied from the dominated lamella to the finer blocks, and their size was reduced and, the volume fraction increased significantly. And thus, the mechanical properties of the alloy are obviously higher than those by conventional metal mold casting alloy.