Enthalpies of mixing of Au–Pb and Ag–Au–Pb liquid alloys at 973 K

The enthalpies of mixing of the gold–lead and silver–gold–lead alloys were determined at 973 K by using a high temperature Calvet calorimeter (400 K < T < 1400 K). The mixing enthalpies of Au–Pb liquid are negative over the entire composition range with a minimum ΔmixHm = −1074 J mol−1 at XAu = 0.40. The enthalpies of formation of ternary liquid alloys have been carried out along the following sections: XAg/XPb = 1/4, XAu/XPb = 1/4 and 2/3 at 973 K. Experimental values of ΔmixHm = f(XAg, XAu) are compared with those predicted from the Kohler, Muggianu and Toop relations. An assessment including the excess ternary parameter is presented.