Thermodynamic investigation on the Mg–Pd intermetallic phases

New thermodynamic information on Mg–Pd alloys has been obtained in the Mg-rich part by using a high temperature direct drop calorimeter and a high sensitive Differential Scanning Calorimeter (DSC). The calorimetric results have been validated by X-ray Powder Diffraction and Scanning Electron Microscopy coupled with Electron Probe Microanalysis analyses. The following values (kJ∙mol-atom-1) of the enthalpy of formation at 27 °C were obtained: -(28.2 ± 1) for Mg6Pd and -(39.5 ± 2.8) for Mg5Pd2 intermetallic phases. DSC has been employed to determine the transformation temperatures in the Mg-rich region: the congruent melting behaviour of the Mg6Pd and Mg5Pd2 phases was confirmed at a temperature of (568 ± 1) °C and (691 ± 1) °C, respectively and for the L¢(Mg) + Mg6Pd eutectic reaction, a temperature of (530 ± 1) °C was measured. In addition, a melting enthalpy of DfusH = (7.4 ± 0.1) kJ∙mol-atom-1 and of (8.3 ± 0.1) kJ∙mol-atom-1 for Mg6Pd and Mg5Pd2, respectively, was obtained.