Enthalpy of formation of the La–Mg intermediate phases

The aim of this work is to complete the available set of thermodynamic data on the La–Mg system in order to get reliable optimisation of this system by the CALPHAD method. Indeed the CALPHAD method requires a large set of consistent input data including both phase diagram and thermodynamic data. The enthalpies of formation of the La–Mg intermediate compounds were determined at 298 K by means of solution calorimetry in liquid Sn in a Tian–Calvet calorimeter. In these experiments, the partial enthalpies of solution of the compounds at infinite dilution in liquid tin were measured at 665 K. The enthalpies of formation of LaMg, LaMg2 and La2Mg17 compounds were also calculated at 0 K by density functional theory to compare experimental and calculated values.