Simulations of the Initial Stages of Blistering in Helium Implanted Tungsten

Abstract

The initial stages of blistering in W due to low-energy He implantation have been investigated by molecular dynamics simulations. The calculations were carried out on a block of (001) W at 0 K, for 100 eV He ions impinging on it. This energy is far below the threshold energy needed by the projectiles to create lattice displacements in W, which is about 0.50 keV. By visual inspection of the motion of W atoms during implantation, we find that an important mechanism for growth of small He bubbles (containing up to about 10 atoms) is the formation of (111) self-interstitial crowdion atoms. The formation of the interstitial relieves the high internal pressure in the He bubbles.