Experimental investigation and thermodynamic calculation of the Co-Zn-Zr ternary system

The phase equilibria of the Co-Zn-Zr ternary system were systematically studied by combining experimental analysis and thermodynamic modelling. The 450 degrees C isothermal section at the Zn-rich corner and the 600 degrees C isothermal section of Co-Zn-Zr system were studied by means of scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Seventeen and ten three-phase regions were obtained at 600 and 450 degrees C isothermal sections, respectively. Three stable ternary compounds named tau 1 (ZrCo2Zn20), tau 2 (Zr5Co3Zn12) and tau 3 (Zr10Co3Zn7) were found in the 600 degrees C isothermal section. Among them, the Bravais lattice symmetry of the tau 2 phase is a simple tetragonal lattice, and its lattice parameters are a = 8.945 angstrom, b = 8.945 angstrom, c = 11.737 angstrom and alpha = beta = gamma = 90 degrees. Based on the comprehensive evaluation of the current experimental results and the data reported in the literature, the thermodynamic description of the system was developed using the CALPHAD technique. A set of self-consistent thermodynamic parameters for the Co-Zn-Zr ternary system was obtained with good agreement between the experimental and calculated results.

Automated summary

The phase equilibria of the Co-Zn-Zr ternary system were studied using experimental analysis and thermodynamic modelling. Different phase regions were observed at different temperatures, and three stable ternary compounds were discovered.