Thermal transport properties of multiphase sintered metals microstructures. The copper-tungsten system: Experiments and modeling

Abstract

The thermal diffusivity of Cu-W sintered alloys microstructures is measured at room temperature at different compositions, using rear face flash experiments. The samples are synthesized with the Spark Plasma Sintering technique. The resulting microstructures are slightly porous and consist of angular nanoscale grains of tungsten with medium sphericity in a copper matrix. The tungsten particles are at the nanoscale with an average grain size of 250 nm in contrast to the copper matrix for which the average grain size lies in the range 20 μm–30 μm; this is large enough to avoid the grains boundary effect upon the thermal transport. The overall porosity of the microstructures lies within the range: 6%≤P≤12%. Along with the experimental work, a predictive model describing the effective thermal conductivity of multiphasic macrostructures is proposed in order to explain the obtained experimental results. The model was developed based only on physical considerations and contains no empirical parameters; it takes into account the type of microstructure and the microstructure parameters: porosity, grain shape, grain size, and grain size distribution. The agreement between the experiments and the model is found to be excellent.