Thermodynamic modeling of Au-Ce-Sn ternary system

Phase relationships in Au-Ce-Sn ternary system have been thermodynamically modeled by using the CALPHAD technique. Out of the three binary systems, two systems (i.e. Au-Ce, and Sn-Ce) were thermodynamically assessed in this work, and the description of the third one (i.e. Au-Sn) was significantly improved from that of the previous one by adopting the recently published lattice stability of Sn(hcp). Ab initio calculations were employed to support the present thermodynamic assessment via calculating the enthalpies of formation of the relevant binary compounds as well as those of the two stoichiometric ternary compounds. All the intermetallic compounds in binary systems and two out of the seven ternary compounds were treated as stoichiometric phases. The other five ternary compounds were modeled with two or three sublattice sites based upon their homogeneity ranges. The solution phases, including liquid, fcc, bcc, hcp and dhcp, were modeled as substitutional solution phases. The Au-Ce-Sn ternary system was assessed by utilizing the thermodynamic descriptions of the three binary systems, and by taking into account the recently reported isothermal section at 750 °C. The set of thermodynamic parameters, obtained in this work, can be used to reproduce the experimentally determined phase equilibria at 750 °C. Besides, the liquidus projection was extrapolated utilizing the present database.