The solubility of carbon in α-Fe as a function of lattice strain and in the vicinity of the Σ5(310)[001] symmetrical tilt grain boundary was calculated using ab initio methods based upon density-functional theory. The results were compared to four different empirical potentials: the embedded-atom method potentials of Lau et al., Ruda et al. and Hepburn et al., and the modified embedded-atom method potential of Lee. The results confirmed that the solubility of carbon in body-centered-cubic Fe increased under local volume expansion and provided quantitative data for the excess enthalpy to be used in thermodynamic databases. According to this study, the excess enthalpy obtained from density-functional theory was more strain-sensitive than those obtained from tested empirical potentials. The comparison of the applied methods also revealed that, among the empirical potentials, the modified embedded-atom method was most appropriate for describing the solubility of C in body-centered cubic Fe under strain. The differences between the four empirical potentials stemmed from differing parameterizations of the embedded-atom method potentials and, in the case of the modified embedded-atom method, from the altogether different formalism that also included angular dependent terms in the binding energy.

Solubility of Carbon in α-Iron under Volumetric Strain and Close to the Σ5(310)[001] Grain Boundary: Comparison of DFT and Empirical Potential Methods. E.Hristova, R.Janisch, R.Drautz, A.Hartmaier: Computational Materials Science, 2011, 50[3], 1088-96