| When the calculation of phase diagram (CALPHAD) method is applied to the Au-Ag-Al ternary phase diagram, the accuracy of three marginal binary phase diagrams (Au-Al, Au-Ag，Ag-Al) has a great impact on the calculating results. At present, there are some contraditions in the Au-Al marginal binary phase diagram. Therefore, based on a comprehensive evaluation of experimental data for the Au-Al system, the equilibrium phase diagrams were optimised and calculated by using a solid solution model to describe the Gibbs free energy of the liquid, Bcc and Fcc phases in the Au-Al system, and by using the sublattice models (Al)(Au)4, (Al)3(Au)8, (Al)(Au)2, (Al)(Au) and (Al,Au)2(Al,Au) to describe the AlAu4, Al3Au8, AlAu2, AlAu and Al2Au phases. A set of reasonably self-consistent thermodynamic parameters was obtained via optimizing with Pandat software. Au-Al phase diagrams calculated in this way agreed well with the experimental and thermodynamic data. Combined with thermodynamic parameters of Au-Ag and Ag-Al, the Au-Ag-Al liquid-phase, surface projections and isothermal cross-sections were calculated. The liquid-phase surface projections revealed the existence of eight four-phase equilibrium reactions in this ternary system, and these results may be helpful in studying the Au-Ag-Al alloys. |
