Numerical simulations of thermal conductivity in void-containing tungsten: Topological feature of voids

Abstract

Tungsten, as a promising candidate for plasma-facing material in the advanced fusion reactors, has to suffer heat loading and high-energy particle irradiation. Since numerous voids form in the grain interior and on the grain boundary during irradiation, the thermal transfer capacity of tungsten would face a grand challenge. Herein, we systematically investigate the thermal conductivity of void-containing tungsten using finite element method. To understand the relation between the topological features of void and the corresponding thermal response within a wide temperature range, we analyze the thermal conductivity of tungsten by considering the arrangements, shapes and rotation angles of voids. The effects of intra- and inter-granular voids on the heat transmission are examined. The numerical results show how the thermal conductivity of single-crystal tungsten can be independent of void distribution pattern and how the void shape can lead to an anisotropic effective thermal conductivity. The predicted thermal conductivities are compared with those of well-known models and experimental data. Apart from voids, the proportion of grain boundary is also considered to analyze its effect on the thermal resistivity. Finally, we show how the spatial distribution of voids influences the heat flow inside the crystalline phase and across the grain boundary.