Effects of external magnetic field on the diffusion coefficient and kinetics of phase transformation in pure Fe and Fe–C alloys

The calculation model of the diffusion coefficient under an external magnetic field was presented. The self-diffusion coefficient in the αFe (bcc) phase and the diffusion coefficients of Ni and Co in the αFe phase were calculated. The calculated results indicate that the diffusion coefficient decreases with the decreasing of temperature and increasing of external magnetic field intensity. The kinetics of the γFe (fcc) → α Fe (bcc) phase transformation under an external magnetic field in pure Fe and Fe-1 at. % C alloy were also studied. It is found that grain refinement under an external magnetic field is caused by the increasing of nucleation rate and growth rate as well as the short transformation time.