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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T_1相与镁基固溶体相平衡,且α-Mg+T_1两相区明显缩小.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+Mg_2Ca+T_1,α-Mg+T_1+Liq,Liq+T_1+T_2和Liq+T_2+Mg_2Zn_3.
The solubility of Mg-Zn-Ca-based Mg-Zn-Ca-based solid solution at 400 ℃ and the equilibrium between Mg-Zn-Ca-based solid solution and the compound were studied by SEM, EPMA, XRD and DSC.The results showed that Ca, T_1 and T_2 phases are still the main ternary compounds rich in Mg at 400 ℃, but only the T_1 phase equilibrates with the Mg-based solid solution and the α-Mg + T_1 two-phase region shrinks significantly. At 400 ℃, Mg -Zn-Ca-based low Ca side of the existence of a liquid phase with magnesium-based solid solution phase equilibrium, the Ca content of less than 8.4% (atomic fraction); but Zn / Ca value of less than 1.7 ternary alloy will not have liquid Phase exists in the 400 ℃ isothermal section of the Mg-Zn-Ca low-temperature side of the Mg-Zn-Ca system: α-Mg + Mg_2Ca + T_1, α-Mg + T_1 + Liq, Liq + T_1 + T_2 and Liq + T_2 + Mg_2Zn_3.