Understanding the thermal conductivity of pristine W and W–Re alloys from a physics-based model

Abstract

Tungsten (W) and tungsten-rhenium (W–Re) alloys are considered as the preferred plasma facing materials and structure materials for advanced fusion reactors. Thermal conductivity is one of the critical concerns for their materials applications. Although the steady-state heat transfer model can be utilized to evaluate the thermal conductivity variation in a traditional way, the thermal parameters of the material must be known beforehand. However, there are rare studies on the role of phonon and electron scattering mechanisms over a wide temperature range during the thermal transport process. In this paper, a physics-based model is established to predict the thermal conductivities of pristine W and W-xRe alloys (x = 1, 3, 5, 10, 25 wt%) from 300 to 1200 K. The model, which contains various scattering mechanisms, can be used to assess the effects of dislocation, grain size and solute rhenium on the total thermal conductivity. The temperature-dependent thermal conductivity predicted by the physics-based model agrees well with the reported data. Our simulation results reveal that 1010 - 1013 m−2 dislocation densities in tungsten has almost no impact on the change of thermal conductivity, while an obvious decrease is observed at temperature below 400 K if dislocation density exceeds 1014 m−2. Both small grain size and more solute rhenium in W–Re alloy can severely degrade the ability of heat transport.