The phase equilibria of the Cu–Zr–V system supported by experiments and CALPHAD method

The phase equilibria of the Cu–Zr–V system at 900, 800, 700 and 600 °C were determined by X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersive X-ray spectrometry (EDS). The solubilities of third element in the binary phase i.e., V₂Zr, Cu₅Zr, Cu₅₁Zr₁₄, Cu₁₀Zr₇, Cu₈Zr₃, CuZr and CuZr₂, were determined. Two ternary compounds, CuZrV and CuZr₆V₃, were identified, with the CuZr₆V₃ phase being newly discovered. Compositional analyses revealed the CuZrV phase as Cu_28.8Zr_39.8V_31.4at 900 °C and Cu_33.5Zr_37.3V_29.2 at 800 °C, while the CuZr₆V₃ phase exhibited compositions of Cu_9.0Zr_57.8V_33.2 at 900 °C and Cu_5.9Zr_57.4V_36.7 at 700 °C. A thermodynamic assessment of the Cu-Zr-V system was performed using the CALPHAD (CALculation of PHAse Diagrams) approach, employing substitutional solution models for solution phases and sublattice models for intermetallic compounds. The ternary compounds CuZrV and CuZr₆V₃ were described as (Cu)₁(Zr)₁(V)₁ and (Cu)₁(Zr)₆(V)₃, respectively. A set of self-consistent thermodynamic parameters of the Cu–Zr–V system was obtained. The isothermal sections at 900, 800, 700 and 600 °C and liquidus projection were calculated, and the reaction scheme was constructed. The calculated phase equilibria show good agreement with experimental observations.