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 following analytical expressions for Δ H mix, derived from the experimental results: Cu–Ag: Δ H mix= X Cu X Ag(16,959−7,620 X Ag+4,287 X Ag 2) J/mol Cu–Au: Δ H mix= X Cu X Au(−29,506−2,616 X Au+9,360 X Au 2) J/mol Ag–Au: Δ H mix= X Ag X Au(−16,803−3,233 X Au+4,525 X 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. Watanabe, Met. Trans. 13B (1982) 391–401] and of Topor and Kleppa [L. Topor, O.J. Kleppa, Met. Trans. 15A (1984) 203–208], obtained by dropping one of the two components into the high-temperature calorimeter from room temperature.