Diffusion of Bi-Interstitials in the Fe and V BCC Metals Subjected to Different Types of External Loads

Anisotropic diffusion of radiation defects in fields of elastic strains created by external loads has a substantial effect on the radiation deformation of crystals (for example, radiation creep); therefore, it is necessary to know how to determine the effect of external elastic fields on the diffusion characteristics of radiation defects in order to develop physical models of crystal deformation under damaging irradiation. In this study, methods are developed for molecular dynamics simulation of the diffusion of radiation defects in bcc crystals subjected to various types of loads (hydrostatic and shearing loads) and for determining the diffusion characteristics of defects by the calculated diffusion trajectories. These methods were used to calculate the effect of external hydrostatic and shearing strains (in the range from –1 to + 1%) on the diffusion tensor of bi-interstitials in the Fe and V bcc metals in the temperature range of 350–800 K. Tensors of bi-interstitials and effective dipole tensors of saddle configurations of bi-interstitials in Fe and V are determined from the strain dependences of the diffusion tensor.