Thermodynamic description of the Au–Ag–Pb ternary system

Combined with previous assessments of the Au–Ag, Ag–Pb and Au–Pb binary systems, thermodynamic description of the Au–Ag–Pb ternary system has been performed using the CALPHAD method and Thermo-calc® software package on the basis of the reported experimental information. The solution phases, including liquid and fcc_A1, are modeled as substitutional solutions, of which the excess Gibbs energies are expressed by the Redlich–Kister–Muggianu polynomial. The solubility of Ag in the Au–Pb intermediate compounds, Au2Pb, AuPb2 and AuPb3, is not taken into account due to the lack of experimental data. Thermodynamic properties of liquid alloys, liquidus projection and several vertical sections of this ternary system have been calculated, which are in reasonable agreement with the reported experimental data. Finally, a set of self-consistent thermodynamic parameters formulating the Gibbs energies of various phases in the Au–Ag–Pb ternary system has been obtained in the present work.