Thermodynamic assessment of the Ni–Sc binary system

• Phase equilibria and thermochemical properties for the Ni–Sc system are evaluated.
• The self-consistent thermodynamic parameters are obtained for the Ni–Sc system.
• A segmented function is used to fit Cp of ScNi2 in low and high temperature ranges.

On the basis of the experimental data of the phase equilibria and the thermochemical properties, a critical evaluation for the Ni–Sc binary system has been carried out using the CALPHAD (Calculation of Phase Diagrams) method. The associated model is used for the liquid phase containing the constituent species Ni, Sc and ScNi. The terminal solid solutions Fcc_A1 (Ni), Hcp_A3 (Sc), and Bcc_A2 (Sc) are described by the solution model with the Redlich–Kister polynomial. The intermetallic compounds, ScNi5, Sc2Ni7, ScNi and Sc2Ni, are treated as strict stoichiometric compounds. The compound with a homogeneity range, (ScNi2), is modeled using two sublattices as (Sc,Ni)0.333(Sc,Ni)0.667. A set of self-consistent thermodynamic parameters for the Ni–Sc binary system is obtained. The calculated results agree well with the available experimental data from literatures.