A critical thermodynamic assessment of the Mg-Ni, Ni-Y binary and Mg-Ni-Y ternary systems

A thorough review and critical evaluation of phase equilibria and thermodynamic data for the phases in the Mg-Ni-Y ternary system have been carried out over the entire composition range from room temperature to above the liquidus. 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. The Gibbs energies of the different phases have been modeled, and optimized model parameters that reproduce all the experimental data simultaneously within experimental error limits have been obtained. For the liquid phases, the modified quasichemical model is applied. A sublattice model within the compound-energy formalism is used to take proper account of the structures of the binary intermediate solid solutions. The Mg-Ni and Ni-Y binary systems have been re-optimized based on the experimental phase equilibrium and thermodynamic data available in the literature. The optimized thermodynamic parameters for the Mg-Y system are taken from the previous thermodynamic assessment of the Mg-Cu-Y system by the same authors. The constructed database has been used to calculate liquidus projection, isothermal and vertical sections which are compared with the available experimental information on this system. The current calculations are in a good agreement with the experimental data reported in the literature. (C) 2009 Elsevier Ltd. All rights reserved.