Atomic scale study of single self interstitial atom diffusivity in bcc Fe-Cr using molecular dynamics simulation

Two many-body interatomic potentials for the atomistic simulation of radiation effects in the Fe-Cr system have been recently proposed. In the present work, these potentials are used to calculate the diffusivity of single self-interstitial atoms (SIA) in an -Fe matrix with randomly distributed chromium atoms, by means of classical molecular dynamics (MD). The main difference between the two potentials used consists in a different prediction of the most stable interstitial configuration in Fe and Fe-Cr. The mechanisms of diffusion in pure bcc iron and in Fe-Cr alloys of different concentrations are analysed and a slowing down of SIA motion caused by crowdion defocussing and binding energy of SIA with solute atoms is found in the alloy. The actual diffusion coefficient of SIA in concentrated alloys is expected to be concentration dependent.