Abstract

Thermodynamic modeling of the Mg-Cu-Y system is carried out as a part of thermodynamic database construction for Mg alloys. This system is being modeled for the first time using the Modified Quasichemical model which considers the presence of short range ordering in the liquid. A self-consistent thermodynamic data base for the Mg-Cu-Y system is constructed by combining the thermodynamic descriptions of the constituent binaries, Mg-Cu, Cu-Y, and Mg-Y using a suitable ternary extrapolation technique. All the three binaries have been re-optimized based on the experimental phase equilibrium and thermodynamic data available in the literature. The constructed database is used to calculate and predict the thermodynamic properties, binary phase diagrams and liquidus projections of the ternary Mg-Cu-Y system. Calculated phase diagrams and the thermodynamic properties such as activity, enthalpy of mixing and partial Gibbs energy of the binary liquid alloys are found to be in good agreement with the experimental data reported in the literature. Moreover, for the Mg-Cu-Y ternary system, isothermal sections, vertical sections and polythermal sections are calculated, and the invariant reaction points are predicted for the first time