Calorimetric studies and thermodynamic modelling of liquid Mg-Pb-Pd alloys

Abstract

The thermodynamic properties of liquid Mg-Pb-Pd alloys had not yet been studied. Therefore, with the use of a MHTC 96 drop calorimeter, the first time, calorimetric measurements of the partial and integral mixing enthalpies of liquid Mg-Pb-Pd alloys were performed. Calorimetric measurements of five series of liquid alloys with compositions (Mg0.75Pb0.25)1-xPdx, (Mg0.50Pb0.50)1-xPdx (two series of this alloy were evaluated), (Mg0.25Pb0.75)1-xPdx, and (Pb0.90Pd0.10)1-xMgx were performed at a temperature of 1012 K. Thereafter, based on the obtained data on the mixing enthalpy and taking into account the thermodynamic properties of binary subsystems described by the Redlich-Kister equation, ternary excess term of the Mg-Pb-Pd liquid phase was evaluated by the Muggianu model. Using home-made software (TerGexHm), thermodynamic optimization resulting in ternary optimized parameters was done. The presented calorimetric measurements represent the first step in the investigation and assessment of ternary Mg-Pb-Pd system. Overall, the intention of the authors is to model the phase equilibria in both binary and ternary systems.