Surface modification and deuterium retention in rhenium doped tungsten exposed to low energy deuterium plasma

Abstract

Surface modification and deuterium (D) retention in rhenium (Re) doped tungsten (Namely, W-5 wt.% Re) exposed to 100 eV deuterium plasma with a constant flux of 1.8 × 1021 D/m2/s were investigated. All the samples were exposed to D plasma at three types of exposure conditions, namely, exposure with doses of 1.3 × 1025 D/m2 and 2.6 × 1025 D/m2 at 470 K as well as exposure with dose of 5.2 × 1025 D/m2 at 506 K. Before irradiation, it was found that Re doping caused the decreases of hardness and lattice constant. As the samples were exposed to D plasma with the fluence of 1.3 × 1025 D/m2 at 470 K, many deuterium blisters with a size of tens nanometer were observed on surface of pure tungsten (W). While for W-Re alloy, only strip-like nanostructures can be found. Meanwhile, Re doping inhibited the surface blistering but increased total deuterium in W under this exposure condition. As the exposure fluence up to 2.6 × 1025 D/m2, it was found that both the blisters and total deuterium retention in W was restrained by Re doping. As the exposure fluence and temperature increased simultaneously, surface blistering on W-Re alloy was further suppressed compared to pure W.