中文摘要：

采用合金法，利用XRD、SEM—EDS测定一系列Mg-Sn-Y三元合金在500℃下富Mg角处相平衡关系及各相平衡成分，建立Mg—Sn-Y三元系在500℃下富Mg角处的等温截面相图。结果表明：Mg—Sn—Y三元系富Mg角处存在Mg2Sn、MgSnY、Sn3Ys和Mg24＋xY54种化合物与α-Mg固溶体平衡，从而构建3个三相区和4个两相区；Sn在α-Mg基体中的固溶度为2．5％～3．9％（摩尔分数），Y在α-Mg基体中的固溶度为1．1％，但二者不能同时固溶到a-Mg基体中，同时Sn3Y5相中大约可以固溶3．6％～4．1％的金属Mg；由于MgSnY和Sn3Y5等一些高熔点化合物在高温下能够稳定存在，使得Mg—Sn—Y体系有可能成为一种潜在的新型耐热镁合金。

英文摘要：

By equilibrated alloy method the phase equilibria relation and phase equilibria composition of the Mg-riched corner in the Mg-Sn-Y ternary system at 500℃ were determined by XRD and SEM-EDS, thus the isothermal section of this ternary system was constructed. The results show that four intermetallic compounds exist in equilibrium with the a-Mg solid solution, i.e. Mg2Sn, MgSnY, Sn3Y5 and Mg24＋xY5. Therefore, three three-phase regions and four two-phase regions are constructed. The solubility of Sn and Y in the a-Mg solid solution are 2.5%-3.9% and 1.1% （mole fraction）, respectively, but they can not be simultaneously soluted in α-Mg solid solution. In addition, about 3.6%-4.1% Mg is detected in the Sn3Y5 phase. Due to high thermal stability of the compounds such as MgSnY and Sn3Y5, it is thus expected that the Mg-Sn-Y-based alloy could be a promising creep resistant alloy by appropriate alloy design and processing.