Thermodynamic and surface properties of liquid Co–Cr–Ni alloys

• The liquid phases of Co–Cr, Co–Ni and Cr–Ni were modelled by the Quasi Chemical Approximation for regular solutions.
• The excess Gibbs free energy of mixing of the liquid Co–Cr–Ni phase is estimated by the three thermodynamic models.
• Prediction of structure can compensate the lack of structural data of Co–Cr, Co–Ni and Cr–Ni melts.
• Thermodynamic modelling of the surface properties of Co–Cr–Ni melts.
• Weak effects of short range ordering among nearest neighbours in Co–Cr, Co–Ni and Cr–Ni liquid alloys can be deduced.

Direct measurements of bulk and surface properties of liquid alloys at elevated temperatures are often technically difficult or even impossible, and therefore, theoretical models can be used to estimate missing property values. The energetics of mixing in liquid Co–Cr, Cr–Ni and Co–Ni systems has been analysed through the study of the concentration dependence of various thermodynamic, surface (surface tension and surface composition) and structural properties (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) by the first or the Quasi-Chemical Approximation (QCA) for regular solutions, developed by Bhatia and Singh, in the framework of statistical mechanical theory in conjunction with the Quasi-Lattice Theory (QLT). The results obtained for these binary systems have been extended to study the thermodynamics and surface properties of ternary Co–Cr–Ni liquid alloys.