Thermodynamic Properties of Copper-Nickel Alloys Measurments and Assessment

The activity of Ni in solid Cu-Ni alloys was measured at 1000 K using a solid state galvanic cell incorporating CaO-stabilized $ZrO_2$ as the solid electrolyte. The activity of Ni shows positive deviation from Raoult's law over the entire range of concentration. Partial molar entropy of Ni in solid Cu-Ni alloys was measured directly using a newly developed twin solid state thermocell apparatus. A consi-stent set of thermodynamics data for the Cu-Ni system was derived by combining the results of the present study with selected data on enthalpy and free energy of mixing of liquid alloys and the phase diagram. The miscibility gap and the chemical spinodal boundaries obtained from the evaluated data are in good agreement with x-ray & diffuse neutron scattering studies reported in the literature.