Development of thermodynamic database of the Mn-RE (RE = rare earth metals) binary systems

Abstract

In this work, eight Mn-RE (RE = Ce, Pr, Sm, Tb, Er, Tm, Lu, and Y) binary systems were reassessed thermodynamically by the CALPHAD method based on the reported optimizations and experimental information. Self-consistent thermodynamic parameters to describe Gibbs energies of various phases in eight Mn-RE binary systems were obtained. The calculated phase equilibria and thermodynamic properties of eight Mn-RE binary systems are in good accordance with the experimental results. Furthermore, phase equilibria and thermodynamic properties of 13 Mn-RE (RE = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu, and Y) binary systems were discussed systematically in combination with the present calculations and the reported optimizations. A trend was found for the variation of phase equilibria and thermodynamic properties of the Mn-RE binary systems. In general, as the RE atomic number increases, the enthalpies of mixing of liquid alloys as well as the enthalpies of formation of the intermetallic compounds become increasingly negative, and the formation temperatures of the intermetallic compounds become higher. The results provide a complete set of self-consistent thermodynamic parameters for the Mn-RE binary systems, and a thermodynamic database of 13 Mn-RE binary systems was finally achieved.