An isothermal section of the Mg-Nd-Gd ternary system at 723 K was established by diffusion triple technique and electron probe microanalysis(EPMA). Mg3Gd and Mg3Nd form a continuous solid solution(Gd,Nd)3Mg, and a continuous solid solution(Gd,Nd)Mg is also formed between MgGd and MgNd. Mg7Gd, Mg5Gd, Mg2Gd, Mg41Nd5,(Gd,Nd)3Mg and(Gd,Nd)Mg are found in the ternary system. In these intermetallic phases, Mg7Gd has been reported to be a metastable phase in previous literatures. The solubilities of Mg, Gd and Nd in all the phases were detected. Furthermore, four three-phase equilibria, α(Mg)+Mg7Gd+ Mg41Nd5, Mg7Gd+Mg5Gd+Mg41Nd5, Mg5Gd+Mg41Nd5+(Gd,Nd)3Mg and(Gd,Nd)3Mg+(Gd,Nd)Mg+Mg2Gd, were identified in the isothermal section.采用三元扩散偶技术,利用电子探针成分分析,建立Mg-Nd-Gd三元系723 K的等温截面。Mg3Gd和Mg3Nd在三元系中形成连续固溶体(Gd,Nd)3Mg,MgGd和MgNd也形成连续固溶体(Gd,Nd)Mg。在三元系中出现的金属间化合物有Mg7Gd、Mg5Gd、Mg2Gd、Mg41Nd5、(Gd,Nd)3Mg和(Gd,Nd)Mg,其中Mg7Gd在以往的报道中认为是亚稳相。测量了Mg,、Gd和Nd在每相中的溶解度,发现在Mg-Nd-Gd三元系中存在4个三相平衡,它们分别是α(Mg)+Mg7Gd+Mg41Nd5,Mg7Gd+Mg5Gd+Mg41Nd5,Mg5Gd+Mg41Nd5+(Gd,Nd)3Mg和(Gd,Nd)3Mg+(Gd,Nd)Mg+Mg2Gd。
