The Phase Relations Studies of Mg-Zn-RE at 553 K Coupling with Diffusion Triple Technique and Frist Principle Calculations.

The isothermal sections of Mg-Zn-RE(Nd,Gd) ternary system at 553 K were measured with the help of diffusion triple technique. The results show that they were at metastable equilibrium instead of the final equilibrium state. Three ternary phases T1, T3 and T4 in Mg-Zn-Nd system have been detected. Specially, T3 was found out to be an independent ternary phase instead of a binary phase MgNd with very large solubility of Zn. Twelve tri-phases that reached local equilibriums have been identified in Mg-Zn-Nd system at 553 K. Two ternary compounds, W and I, have been found. The binary phases, MgGd and MgGd, have a solution of 3.0 at.% and 4.3 at.% Zn, respectively. The phase T-MgRE type found in Mg-Zn-Nd agrees with the calculated result from First-principle. [ABSTRACT FROM AUTHOR]