A <100> edge dislocation core system with a C atom was investigated in the α phase by using a molecular cluster method and a self-consistent discrete variational method which was based upon density functional theory. A cluster model which contained 96 atoms was used to simulate the local environment of the edge dislocation, and the results showed that the C atom moved from the compression side to the dilated region. It fell into a flat tetrahedral interstice which was made up of 4 adjacent host atoms. Characteristic parameters were deduced which included the structural energy, the interatomic energy, the partial density of states and the charge-density difference. The results suggested that the C atom remained at a favourable site in the tetrahedron and formed strong covalent-like bonds with its adjacent host atoms. A marked charge redistribution, and a large binding energy drop in the dislocation core system, indicated the formation of a C-impurity plus Fe edge dislocation complex. This, in turn, implied a trapping effect of the dislocation core upon the C atom.

The Electronic Effect in the <100> Edge Dislocation Core System with a Carbon Atom in α-Iron - a First-Principles Study. Y.Niu, S.Y.Wang, D.L.Zhao, C.Y.Wang: Journal of Physics - Condensed Matter, 2001, 13[19], 4267-76