Experimental investigation and CALPHAD modeling of the Cu–Cr–Si ternary system

Abstract

The phase equilibria of the Cu–Cr–Si ternary system were investigated via thermodynamic modeling coupled with key experiments. Seventeen ternary alloys were prepared to determine the isothermal sections of the Cu–Cr–Si system at 700 and 800 °C by combining X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS). No ternary compound was found. The solubilities of the third element in binary compounds in the Cu–Si and Cr–Si systems were measured. Based on the thermodynamic descriptions of three constitutive binary systems available in the literature as well as the experimental phase equilibria data obtained from the present work and literature, thermodynamic re-assessment of the Cu–Cr–Si system was carried out by the CALPHAD (CALculation of PHAse Diagrams) approach. The substitutional model and sublattice model were used to describe the solution phases and intermediate phases, respectively. A set of thermodynamic parameters of the Cu–Cr–Si system was obtained. The calculated isothermal sections and vertical section are in good agreement with most of the reliable experimental data. The liquidus projection and reaction scheme of the Cu–Cr–Si system over the whole composition were also presented.