Guanglong Xu, Yu-Wen Cui, Houjun Fei, Ligang Zhang, Feng Zheng, Libin Liu, Zhanpeng Jin
March 26, 2012
Phase equilibria of the Gd–Ni binary and Mg–Ni–Gd ternary systems were critically investigated using equilibrated alloys and differential scanning calorimeter measurements. The phase diagram of the Gd–Ni binary system was updated from scanning electron microscopy with energy-dispersive X-ray spectrometry, X-ray diffraction, and differential scanning calorimeter results obtained on binary samples over the entire composition range. Major changes made in the present work include the absence of the Gd 3 Ni 2 and GdNi 4 compounds and the congruent melting point of the GdNi compound. An isothermal section of the Mg–Ni–Gd ternary system at 673 K was constructed from the investigations on 22 ternary alloys. In total, six ternary compounds were identified in this work, three of which were observed to crystallize in the Cu 4 MgSn (τ1), Mo 2 FeB 2 (τ2), and Ru 4 Al 3 B 2 -type (τ3) structures, respectively. As in most of the Mg–rare-earth metal–transition metal ternary systems, a long-period-stacking ordered phase was identified to have an 18R structure and a melting temperature of 806 K. Noticeable solid solubility of Ni in the Mg 5 Gd and Mg 3 Gd binary compounds was observed.