Atomistic simulation of mechanical properties of tungsten-hydrogen system and hydrogen diffusion in tungsten

Molecular dynamics simulation is used to systematically investigate mechanical properties of tungsten-hydrogen system and hydrogen diffusion in tungsten. It is found that the tensile strength of tungsten is decreased seriously by the formation of hydrogen bubbles, and the intrinsic mechanism is discussed by deformation dislocations. The present calculation also reveals that the hydrogen clusters in tungsten would be hard to diffuse, and may finally accumulate and form bubbles. In addition, the uniaxial and isotropic tensile strains have different effects on the diffusivity of hydrogen clusters, and the mean square displacements of H clusters diffusing along several directions under uniaxial and isotropic tensile strains are derived and compared with each other. The simulated results agree well with experimental evidence and calculated data available in the literature.