Thermodynamic study of solid copper-nickel alloys by use of copper-beta-alumina

Copper activity in solid copper-nickel alloys was measured by electromotive force (EMF) technique incorporating the partially exchanged (Cu+-Na+)-β″-alumina as a solid electrolyte for temperatures between 870 and 1300 K. The activities of copper and nickel in the solid solution at these temperatures exhibited positive deviations from Raoult's law. The activity coefficients of copper and nickel at infinite dilution at 973 K were estimated to be 5.55 and 3.71, respectively. Furthermore, the free energies, enthalpies and entropies of mixing were derived from EMF data.