Surface modification of W–V alloy exposed to high heat flux helium neutral beams

Surface modification of tungsten vanadium (W–V) alloy under high heat flux helium particle bombardment has been studied. W–5 wt.% V samples were irradiated by repeated helium pulses at a peak surface temperature of 900 °C and 1800 °C, respectively, in the neutral beam facility GLADIS. The effect of helium fluence on the surface morphology changes was investigated by increasing the helium fluence from 1  ×  1022 m−2– 2  ×  1022 m−2. Blistering is the typical structure after the repeated helium pulses loading at 900 °C, and it becomes more severe with increased fluence. A porous structure becomes dominant at 1800 °C. An evolution of a porous structure to coral-like structure is observed as fluence increases. In addition, the three typical regions in the W–5V, W-enriched region, W–V solid solute region, and V-enriched region, exhibit different damage features. The W–V solid solute region shows better surface damage resistance compared to the other two regions.