Experimental investigation and CALPHAD modeling of thermal conductivities of the Cu–Ag–Cr–Zr system

Thermal conductivity is one of the important thermophysical properties for describing the ability of a material to transfer heat. The thermal conductivities and microstructures of Cu–Ag, Cu–Cr and Cu–Zr binary alloys were experimentally investigated. 11 equilibrated binary alloys were designed and prepared annealed at 600 °C for 60 days. Their phase equilibria and compositions were analyzed by scanning electron microscopy with energy dispersive X-ray spectrometry (SEM/EDS), and the thermal diffusivities at 20, 100, 200 and 300 °C and the densities at room temperature were measured by laser flash analysis (LFA) method and Archimedes method, respectively. The heat capacities of alloys at different temperatures were calculated through the thermodynamic database, and then the experimental thermal conductivities of each alloys were obtained by the specific conversion equation. Based on the experimental data from the literature and present work, the thermal conductivities of pure elements, the solid solution phases, the stoichiometric compounds and the two-phase regions were evaluated by the CALPHAD (CALculation of PHAse Diagrams) approach. A set of self-consistent thermal conductivity parameters for description of the Cu–Ag–Cr–Zr system was obtained. Comprehensive comparisons between the calculated and experimental results show that the experimental thermal conductivities were satisfactorily accounted for by the present modeling. The present research results can provide important thermal conductivity information for designing new copper alloys and enrich the thermophysical database of copper alloys.