Mixing enthalpies of liquid alloys and thermodynamic assessment of the Cu–Fe–Ni system

Abstract

The partial mixing enthalpy of nickel in ternary liquid alloys of the Cu–Fe–Ni system is studied by the calorimetric method at 1873 K and xNi = 0–0.55. The $$ \Delta {\overline H_{Ni}} $$ function has mainly negative values over the composition range of interest. The results show the key role of binary interactions in the formation energetics of liquid alloys in the Cu–Fe–Ni system. A set of self-consistent parameters of thermodynamic models of the phases is obtained taking into account experimental data on the thermodynamic properties of liquid and solid solutions and data on stable phase transformations. The thermodynamic assessment of the system is carried out in the framework of the CALPHAD method. The calculated liquidus surface and isothermal and vertical sections of the phase diagram are in satisfactory agreement with corresponding experimental data. The metastable miscibility gap of supercooled liquid alloys in the Cu–Fe–Ni system is calculated.