中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 23 No. 4 April 2013 |
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. IMDEA Materials Institute, Madrid 28040, Spain;
3. Key Laboratory of Non-ferrous Materials Science and Engineering of Ministry of Education,Central South University, Changsha 410083, China）
Abstract:The phase equilibria in Mg-rich corner of Mg-Ca-Gd and Mg-Ca-Nd ternary systems at 400 °C were determined through the equilibrated alloy method by using XRD, SEM, EPMA and DSC. Partial isothermal sections in Mg-rich corner of Mg-Ca-Gd and Mg-Ca-Nd ternary systems at 400 °C were constructed from 13 alloys. A three-phase region of α-Mg, Mg41RE5 and Mg2Ca was determined in both ternary systems. It is formed by a similar ternary eutectic reaction L→α-Mg+Mg2Ca+Mg41RE5 at 499.6 °C and 505.6 °C, respectively. It is found that the maximum solubility of Ca in Mg5Gd is 3.68% (molar fraction) and 3% of Gd can be dissolved in Mg2Ca in the Mg-Ca-Gd system at 400 °C. While in the Mg-Ca-Nd system，the maximum solubility of Ca in Mg41Nd5 is 3.57% and 1.24% of Nd can be dissolved in Mg2Ca at 400 °C. Other three-phase equilibria existing in Mg-rich corner of Mg-Ca-Gd system are α-Mg+Mg5Gd+Τ and Mg5Gd+Mg2Ca+Τ and the three-phase equilibrium in Mg-rich corner of Mg-Ca-Nd system is Mg3Nd+Mg2Ca+ Mg41Nd5.
Key words: Mg-Ca-Gd system; Mg-Ca-Nd system; Mg-rich corner; three-phase equilibrium; solubility
