The influence of microstructural features on the electrical conductivity of solid phase sintered CuCr composites

Copper-Chromium composites (CuCr) are commonly used as contact materials for energy distribution. Since Cu and Cr are mutually nearly insoluble, copper-chromium materials are two-phase composites, usually consisting of chromium particles embedded in a copper matrix. In the present work the influences of microstructural features such as the geometry of the Cr phase, phase boundaries and alien phases being located at them, residual porosity and impurities on the electrical conductivity of powder metallurgically produced CuCr with Cr contents of 25 and 43 wt% are investigated. Specifically, we address the effect of the geometry of the Cr phase on the electrical conductivity of the composite by combining quantitative microstructural analyses with an empirical relationship generated from FEM simulations based on simplified microstructures. The predicted electrical conductivities show considerable deviation from experiment. This deviation is believed to be caused mainly by the presence of the phase boundaries and microstructural features related to them, whereas the influence of porosity and contamination of the copper matrix appears to be small.