Thermodynamic evaluations and optimizations of binary Mg-light Rare Earth (La, Ce, Pr, Nd, Sm) systems

Abstract

Mg-light Rare Earth element (RE: La, Ce, Pr, Nd and Sm) binary systems have been systematically assessed and optimized based on the available experimental data and estimated data by first-principles and Miedema's model. The optimization procedure was biased by putting an emphasis on the observed trends in the thermodynamic properties of Mg–RE phases. The Modified Quasichemical Model, which takes short-range ordering into account, is used for the liquid phase, and the Compound Energy Formalism is used for the solid solutions. Optimized model parameters have been obtained for the Gibbs energy functions of all stable phases, and the model reproduce most critically assessed experimental data. It is shown that the Modified Quasichemical Model used for the liquid alloys permits us to obtain entropies of mixing that are more reliable than those based on the Bragg–Williams random mixing model which does not take short-range ordering into account.