Computer simulation of carbon diffusion and vacancy-carbon interaction in α-iron

Static and dynamic properties of the interstitial carbon atom and vacancy-carbon atom complexes in α-iron are modelled by a molecular dynamics (MD) method using a pair interatomic potential for the iron-carbon interaction and two different many-body potentials for the iron matrix. The diffusion parameters of an interstitial solute in iron are obtained by MD simulation for the first time. The binding energy and migration energy of a vacancy-carbon complex are also obtained: the complex is immobile and has higher energy for dissociation than the carbon atom migration energy. The results are compared with recent ab initio calculations and experimental data from the literature. Experimental data on the recovery stages of electron-irradiated Fe-C are analysed using rate theory equations and found to be consistent with the ab initio calculations for diffusion of a vacancy and its interaction with carbon atoms.