Experimental investigation and thermodynamic assessment of the Ni–Zr–Y ternary system

Abstract

Through the integration of experimental investigations and thermodynamic modeling, a thorough exploration of the phase equilibria in the Ni–Zr–Y ternary system was undertaken. Twenty-six ternary alloys were meticulously prepared to study the isothermal sections at 500 and 700 °C, employing techniques such as X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS). The solubilities of Zr in the Ni–Y binary compounds and Y in the Ni–Zr binary compounds were measured. A ternary compound named τ (Ni₂(Y, Zr)) was confirmed at 700 °C. Utilizing thermodynamic parameters of three binary systems and available experimental phase equilibria data from literature and this work, a thermodynamic assessment of the Ni–Zr–Y system was conducted using the CALPHAD (CALculation of PHAse Diagrams) approach. A set of thermodynamic parameters was obtained and the isothermal sections at 500, 597 and 700 °C were calculated, and the calculated results demonstrated a strong agreement with experimental data. The liquidus projection and reaction scheme of the Ni–Zr–Y system was predicted. This work can be used as a basis for the multicomponent thermodynamic database of Ni-based alloys.