The interaction between point defects and edge dislocation in BCC iron

We present results of atomistic simulations of the interaction between self interstitial atoms and vacancies with edge dislocations in BCC iron. The c alculations are carried out using molecular dynamics with an energy minimiz ation scheme based on the quasi-Newton approach and use the Finnis-Sinclair interatomic potential for BCC iron developed by Ackland et al. Large aniso tropy in the strain field of self interstitials is observed and it causes s trong interaction with edge dislocations even when the defect is located on the dislocation glide plane. For vacancies, the relaxation volume is small er and much more isotropic, which results in a far weaker interaction with the dislocation. A temperature dependent capture radius for vacancies and s elf interstitials is extracted from the simulations. The difference between the capture radii of vacancies and self interstitials Is used to define th e sink strength of the dislocation. Large deviations are observed from the predictions of elasticity based on treating point defects as isotropic dila tational centers. Further, the capture radius of edge dislocations in BCC i ron is observed to be small and is of the or-der of 1-3 nm for self interst itials.