Diffusion Properties of Carbon in Fe-C Alloy using New Tersoff Potential

摘要

Diffusion mechanisms for one to three carbon interstitials in BCC iron are studied using new Fe-C interatomicpotential. Firstly, carbon diffusion and stability are investigated by using nudged-elastic band method. The diffusion pathsare also verified and analyzed by constructing potential energy landscapes. Finally, diffusion rates are calculated basedon the transition state theory at different temperatures to study the precipitation of carbon in iron bulk. For the case of 1C,the diffusion barrier from O-site to 1NN O-site is about 1.106×10~(-19)J. In the case of 2C, two carbon atoms tend to form aC-C pair, where both are shifted off the O-sites. The C-C binding energy is about -0.224×10~(-19)J. In 3C case, the thirdcarbon prefers to bind to 2 pre-located C atoms in the neighbor cells with a binding energy of -1.057×10~(-19)J. In addition,from diffusion rate calculations, it shows that carbon atoms tend to combine to stable pairs instead of larger clusters.