Ternary compounds and solid-state phase equilibria in Mg-rich side of Mg-Zn-Ca system at 300 ℃  

Mg-Zn-Ca系富Mg侧三元化合物及其300℃固态相平衡(英文)

作　　者：李洪晓[1] 任玉平[1] 马倩倩[1] 蒋敏[1] 秦高梧[1] 

机构地区：[1]东北大学材料各向异性与织构教育部重点实验室,沈阳110819

出　　处：《Transactions of Nonferrous Metals Society of China》2011年第10期2147-2153,共7页中国有色金属学报（英文版）

基　　金：Project(50731002) supported by the National Natural Science Foundation of China;Project(20082030) supported by the Natural Science Foundation of Liaoning Province,China

摘　　要：The phase equilibria and compositions in Mg-rich side at 300 ℃ were investigated in Mg-Zn-Ca ternary system through the equilibrated alloy method by using scanning electron microscopy,electron probe microanalysis,X-ray diffraction and transmission electron microscopy.The results show that two ternary compounds T1 and T2 can be in equilibrium with the Mg-based solid solution in Mg-Zn-Ca system.T1 phase is a linear compound with the composition region（molar fraction） of 15% Ca,20.5%-48.9% Zn and balanced Mg at 300 ℃.Its hexagonal structure parameters decrease with increasing Zn content,i.e.a=0.992-0.945 nm,c=1.034-1.003 nm.T2 phase has hexagonal structure with the composition region of 26.4%-28.4% Mg,63.2%-65.5% Zn and 7.1%-8.4% Ca.At 300 ℃,the solubility of Zn in the Mg-based solid solution increases for the addition of Ca,the maximum solubility of Zn is 3.7%.Three-phase fields consisting of--Mg＋Mg2Ca＋T1,--Mg＋T1＋T2,--Mg＋T2＋MgZn and MgZn＋T2＋Mg2Zn3 exist in the Mg-Zn-Ca system at 300 ℃.采用合金平衡组织结构分析法,利用扫描电镜组织观察、电子探针定量成分分析以及X射线衍射和透射电子衍射结构分析,对Mg-Zn-Ca系富Mg区域300°C的相平衡关系及平衡相成分进行研究。结果表明:300°C时,2个三元化合物T1和T2都可与Mg基固溶体相平衡。T1相是一个线性化合物相,成分为15%Ca(摩尔分数),20.5%～48.9%Zn,余量为Mg。T1相为六方晶体结构,晶格常数为:a=0.992～0.945nm,c=1.034～1.003nm,随T1相中Zn含量的增加而减少。化合物T2相也是六方结构,成分为26.4%～28.4%Mg,63.2%～65.5%Zn以及7.1%～8.4%Ca。300°C时,Zn在Mg基固溶体中的溶解度随Ca的加入而增大,最大溶解度达到3.7%。在Mg-Zn-Ca系中300°C等温截面相图的富Mg区域存在着三相区α-Mg+Mg2Ca+T1,α-Mg+T1+T2,α-Mg+T2+MgZn和MgZn+T2+Mg2Zn3。

关 键 词：Mg-Zn-Ca system ternary compound STRUCTURE COMPOSITION phase equilibrium 

分 类 号：TG146.22[一般工业技术—材料科学与工程]