(沈阳工业大学 材料科学与工程学院，沈阳 110870)
摘 要: 利用铜模铸造制备直径为1~4 mm的Mg72−xZn28Cax(x=1~6) 合金，采用XRD、DSC、SEM和力学性能试验机分别对合金的非晶形成能力、相组成、断口形貌和力学性能进行研究。结果表明：在x为3、4和5时，Mg72−xZn28Cax合金的非晶形成能力(以直径表示)分别为2、3和2 mm；而当x为1、2和6时，Mg72−xZn28Cax合金的非晶形成能力低于直径为2 mm的；当x为3和5时，直径为2 mm的非晶态合金的屈服强度分别为591 MPa和662 MPa，塑性变形量分别为0.5%和0.2%；直径为3、2和1 mm的Mg68Zn28Ca4非晶合金的屈服强度分别为540、611和610 MPa，塑性变形量分别为0.48%、1.28%和6.2%，Mg68Zn28Ca4非晶合金是目前所报道的塑性变形量最大的镁基非晶合金；单位剪切面上弹性能的减少及其分布均匀性的改善是样品尺寸减小促使塑性应变量提高的主要原因。
关键字: Mg-Zn-Ca合金；非晶形成能力；塑性应变；尺寸效应
Mg-Zn-Ca alloys
（School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China）
Abstract:The as-cast Mg72−xZn28Cax (x=1−6) alloys with diameter size of 1−4 mm were fabricated by using copper mold casting method. The glass forming ability (GFA), phases constituent, fracture surfaces and mechanical properties were investigated by X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results show that the GFA for alloys with x of 3, 4 and 5 are 2, 3 and 2 mm in diameter, respectively. While the GFA for alloys with x of 1, 2 and 6 is lower than that of alloy with 2 mm in diameter. The yield strength and plastic strain are 591 MPa and 0.5% for alloy with x of 3, 662 MPa and 0.2% for alloy with x of 5. Furthermore, the yield strength and plastic strain for Mg68Zn28Ca4 bulk metallic glass with diameters of 3, 2 and 1mm are 540 MPa and 0.48%, 611 MPa and 1.28%, 610 MPa and 6.2%, respectively. The Mg68Zn28Ca4 amorphous alloy shows the highest plastic strain in Mg-based bulk metallic glasses that have ever reported. The enhanced plastic strains with the reduction of sample size were suggested to come from the elastic energy reduction in a unit area on the shear plane as well as its homogeneous distribution in the sample.
Key words: Mg-Zn-Ca alloy; glass-forming ability; plastic strain; size effect
