Diffusion mechanisms in the Fe_3Si alloys

In this paper, the possible reasons for the high thermal vacancy concentration and the low migration barriers for the Fe atom diffusion in the stoichiometric D0 3 structure Fe 3Si have been discussed. The high thermal vacancy concentration was attributed to the compression of Fe-Fe atomic pairs and the tension of Fe-Si atomic pairs in Fe 75 Si 25 . The deformations (compression or tension) of the atompairs increase the interatomic potentials and thus decrease the enthalpies of vacancy formation. The low migration barriers for the Fe atom diffusion in Fe 75 Si 25 were related to the symmetric property of the triangular barriers. Additionally, it was considered that the Si atoms in Fe 3Si could probably migrate via nearest neighbour jumps without disturbing the long range order of atomic arrangements, provided that during the diffusion process the residence time on the antistructure sites is very short.