中文摘要：

利用SEM,EPMA,XRD和DSC,对Mg-Zn-Ca系镁基固溶体400℃时的溶解度以及镁基固溶体与化合物之间的平衡相关系进行了研究.结果表明,在Mg-Zn系中加入Ca后,T_1和T_2相在400℃时依然是富Mg角的主要三元化合物,但只有T1相与镁基固溶体相平衡,且α-Mg＋T1两相区明显缩小.400℃时,Mg-Zn-Ca系低Ca侧存在一个可与镁基固溶体相平衡的液相区,其含Ca量小于8.4%（原子分数）;但Zn/Ca值小于1.7的三元合金中不会有液相存在.Mg-Zn-Ca系低Ca侧400℃等温截面相图中存在着4个三相区：α-Mg＋Mg2Ca＋T1,α-Mg＋T1＋Liq,Liq＋T1＋T2和Liq＋T2＋Mg2Zn3.

英文摘要：

Zn addition to the magnesium alloys could result in the age-hardening,and the age-hardening response of Mg-Zn alloys could be further enhanced by the ternary addition of Ca.In order to better understand the mechanism of the Mg-Zn-Ca base alloy design,the solubility of Mg-based solid solution and relative phase equilibrium at 400℃in low-Ca side of the Mg-Zn-Ca system have been investigated by SEM,EPMA,XRD and DSC.It has been shown that T1 and T2 are still main ternary compounds in the Mg-rich corner at 400℃with the addition of Ca to Mg-Zn system,but only T1 phase could be in equilibrium with the Mg-based solid solution,and the two-phase field ofα-Mg＋T1 becomes narrow.The liquid phase with the Ca content less than 8.4%（atomic fraction） exists in the low-Ca side at 400℃,which could be in equilibrium with a-Mg.But liquid phase could not exist in the Mg-Zn-Ca alloys when the Zn/Ca ratio is less than 1.7.At 400℃,there are four three-phase fields consisting ofα-Mg＋Mg2Ca＋T1,α-Mg＋T1＋Liq,Liq＋T1＋T2 and Liq＋T2＋Mg2Zn3 in the Mg-Zn-Ca system,respectively.