A thermodynamic assessment of the Mg–Nd binary system using random solution and associate models for the liquid phase

Abstract

A self-consistent thermodynamic description of the Mg–Nd system is presented. Given the asymmetric shape of the liquidus in the binary phase diagram, the associate model (which captures the chemical short range ordering (CSRO) tendency of the Mg and Nd atoms) for the liquid phase was tested and compared to the random solution model. The results of the optimization show that better agreement with the available experimental data is obtained using the associate model than with the random solution model. The enthalpy of mixing in the liquid is calculated on the basis of the two models for comparison with further experimental investigations. In addition, an experimental study using scanning electron microscopy (SEM) and X-ray diffraction (XRD) has been performed on two alloy compositions to confirm the metastability of the Mg 12Nd phase, for which some confusion appears in the literature.