Surface morphology and deuterium retention in tungsten and tungsten–rhenium alloy exposed to low-energy, high flux D plasma

Highlights: • W and W–5%Re were exposed to low-energy, high flux D plasma at various temperatures. • The temperature dependences of the D retention in these two materials diverged. • It is suggested that ductility of W and W–5%Re materials influences the D retention. - Abstract: Surface topography and deuterium retention in polycrystalline hot-rolled W and W–5%Re have been examined after exposure to a low-energy (76 eV), high flux (around 10²² D/m² s) deuterium plasma to an ion fluence of 10²⁶ D/m² at various temperatures. The methods used were confocal laser scanning microscopy and the D(³He, p)⁴He nuclear reaction at ³He energies varied from 0.69 to 4.0 MeV. During exposure to the D plasma at temperatures in the range from 348 to 673 K, small blisters of size in the range from about 1 to about 15 μm, depending on the exposure temperature, are formed on the W and W–5%Re surfaces. In the W–5%Re, the deuterium retention demonstrates its maximum at exposure temperature of 463 K, while in the W this maximum is shifted to 523 K. A difference in the temperature dependence of the D retention for the W and W–5%Re is explained, as a rough approximation, by temperature dependences of the ductility of these materials