中文摘要：

采用铜模铸造制备直径为3mm的Mg70-xZn2.5Ca5Cux（x=1，2，3．5，5）系列合金。分别采用扫描电镜（SEM）、X射线衍射仪（XRD）、力学性能试验装置研究合金的显微组织、相组成和铸态样品的压缩性能，并对断口形貌进行分析。结果表明：Mg69Zn25Ca5Cul可以形成直径为3mm的非晶合金，其强度和塑性应变分别为690MPa和11．7％。与Mg-Zn-Ca合金相比，其非晶形成能力和塑性应变均有提高。同时这也是目前在直径大于2mm的Mg基非晶合金中所发现的最大塑性应变量。

英文摘要：

Mg70-xZn25CasCux（x=1, 2, 3.5, 5） as-cast alloys with 3 mm in diameter were produced by using copper mold casting method. The microstrucmres, phase constitutes and mechanical properties of as-cast samples were investigated by scanning electron microscopy （SEM）, X-ray diffractometry （XRD） and compression tester. The fracture surfaces were also analyzed by SEM. The results show that the critical sample size for glass formation, the fracture strength and the plastic strain of Mg69Zn25CasCU1 alloy are 3 mm in diameter, 690 MPa and 1.7%, respectively. Both of the glass forming ability and the plastic deformation are improved obviously compared with Mg-Zn-Ca alloys. Up to now the plastic strain is the largest one in the samples with diameter larger than 2 mm for Mg-based bulk metallic glasses.