Enthalpies of Liquid-liquid mixing in the systems Cu-Ag, Cu-Au and Ag-Au by using an in-situ mixing device in a high temperature single-unit differential calorimeter

The enthalpies of mixing of the binary liquid alloys of copper with silver, copper with gold and silver with gold have been re-determined using a new in-situ mixing technique at 1375 +/-2 K. In this paper we report the follow ing analytical expressions for Delta H-mix, derived from the experimental r esults: Cu-Ag: Delta H-mix = XCuXAg(16,959 - 7,610X(Ag) + 4,287X(Ag)(2))J/mol Cu-Au: Delta H-mix = XCuXAu(-29,506 - 2,616X(Au) + 9,360X(Au)(2)) J/mol Ag-Au: Delta H-mix =XAgXAu(-16,803 - 3,233X(Au) + 4,525X(Au)(2)) J/mol We note that in all of these systems the enthalpy interaction parameter is described by a nonlinear relation to the composition. These new results are compared with earlier data of Kleppa and Watanabe [O.J. Kleppa, S. Watanab e, Met. Trans. 13B (1982) 391-401] and of Topor and Kleppa IL. Topor, [O.J. Kleppa. Met. Trans. 15A (1984) 203-208], obtained by dropping one of the t wo components into the high-temperature calorimeter from room temperature. (C) 1999 Elsevier Science S.A. All rights reserved.