Monte Carlo simulation of phosphorus diffusion in α-iron via the vacancy mechanism

• Published in: Philosophical magazine (Abingdon, England) England), 2005-05, Vol.85 (14), p.1539-1555
• Main Author: Barashev, A. V.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Diffusion in solids; Diffusion of other defects; Exact sciences and technology; Physics; Theory of diffusion and ionic conduction in solids; Transport properties of condensed matter (nonelectronic)
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430500036348

Monte Carlo simulations of the vacancy and phosphorus (P) atom diffusion in body centred cubic (bcc) iron are presented. The input parameters for the calculations, namely the activation energies of atomic jumps, have been 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 are 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 is 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.