It was recalled that the diffusional anisotropy of intrinsic point defects was an important factor which governed the behavior of hexagonal close-packed metals which were bombarded with energetic particles. On the other hand, the effects of stress upon diffusion, and its anisotropy, were not well understood. A combination of molecular dynamics and molecular statics methods was used here to investigate the energy states of a self-interstitial in the α-phase. The calculations showed that the most stable configuration of the self-interstitial was a basal-split dumb-bell configuration on the basal plane. Compression along the [00•1] or the [1¯1•0] directions led to an insignificant change in the migration energies, while compression along the [11•0]direction led to a larger migration energy. A significant change in the diffusion anisotropy was observed when a uniaxial compressive stress of 200MPa was applied along the [11•0] direction. The application of a similar stress along the other 2 directions did not produce any substantial change in anisotropy. It was also shown that an applied hydrostatic stress could significantly change the diffusion anisotropy of hexagonal close-packed metals and alloys. Thus, under irradiation, a hydrostatic stress could produce a significant creep-like deformation (with a deviatoric strain rate) via a stress-dependent change in the growth rate.

Atomistic Studies of Stress Effects on Self-Interstitial Diffusion in α-Titanium. M.Wen, C.H.Woo, H.Huang: Journal of Computer-Aided Materials Design, 2000, 7[2], 97-110