Interaction of Carbon and Extended Defects in α-Fe Studied by First-Principles Based Interatomic Potential

In this paper, the interaction of C with edge dislocations in alpha-Fe with Burgers vectors of 1/2 < 111 >, < 100 >, and < 110 > has been investigated using the classical force-field method in conjunction with the newly-developed Tersoff/ZBL interatomic potential of Fe-C. Here, the potential was constructed from the first-principles database containing force and energy information of various defect complexes with C in body centered cubic (BCC) Fe. The interaction of C and dislocations has been analyzed from the viewpoint of Vomnoi volume formed by C and surrounding Fe atoms. It is found that the interaction between dislocations and C is more attractive when the Voronoi volume around C becomes larger. This tendency is similar to the case of grain boundaries reported previously. It is also found that the grain boundaries and dislocations trap C strongly compared to a single vacancy in BCC Fe, and among them more unstable defect structures attract C more strongly. The obtained tendency might offer a useful guideline to analyse the atomistic distribution of C in Fe with extended defects.