Monte Carlo simulations of the vacancy and P atom diffusion in body centred cubic Fe were presented. The input parameters for the calculations, namely the activation energies of atomic jumps, were obtained using a potential set developed recently for a dilute Fe–P alloy using ab initio data. The diffusion coefficients entering equations for the fluxes of vacancies and solute atoms were evaluated. The results show that, in the temperature range of practical importance for P segregation, P atoms move down the vacancy gradient; hence, under irradiation conditions, vacancies should drag P atoms towards sinks of point defects. This was because of the high binding energy between a P atom and a vacancy in the first and second nearest neighbour sites from each other, which allows a vacancy to move around a P atom without loss of bonding and, hence, co-migrate with it.

Monte Carlo Simulation of Phosphorus Diffusion in α-Iron via the Vacancy Mechanism. A.V.Barashev: Philosophical Magazine, 2005, 85[14], 1539-55