Calphad-type assessment of the Pd-Yb binary system supported by first-principles calculations – Part I: A review

Abstract

Abstract Computational thermodynamic method, such as CALPHAD and the first principle calculation, could be combined and would provide a high throughput thermodynamic investigation method. In the present paper, the thermodynamic properties of the Palladium-Ytterbium binary system were optimized using the CALPHAD approach with the aid of the Thermo-Calc software. The liquid phase and the terminal solid solutions: body-centered cubic for γYb and face-centered cubic for βYb, and (Pd) are described by the substitutional solution model with the exponential (Kaptay model) and linear (Redlich-Kister polynomials) models for the temperature dependence of the excess Gibbs energy. The five intermetallic compounds α-PdYb, β-PdYb, α-Pd5Yb3, β-Pd5Yb3, and Pd3M, which have a homogeneity range, are treated as the phases α-PdM, β-PdM, α-M5Yb3, β-M5Yb3, and Pd3M, respectively, by a two-sublattice model with Yb in M5Yb3 and Pd in PdM and in Pd3M on one sublattice and M on the other, where M is used as an abbreviation for a mixture of Pd and Yb. The other intermetallic compounds, PdYb3, α-Pd2Yb5, β-Pd2Yb5, Pd4Yb3, Pd2Yb, α-Pd21Yb10, β-Pd21Yb10, and Pd7Yb are treated as strict stoichiometric compounds.