Ab initio parametrized model of strain-dependent solubility of H in α-iron

The calculated effects of interstitial hydrogen on the elastic properties of α-iron from our earlier work are used to describe the H interactions with homogeneous strain fields using ab initio methods. In particular, we calculate the H solublility in Fe subject to hydrostatic, uniaxial and shear strain. For comparison, these interactions are parametrized successfully using a simple model with parameters entirely derived from ab initio methods. The results are used to predict the solubility of H in spatially varying elastic strain fields, representative of realistic dislocations outside their core. We find a strong directional dependence of the H-dislocation interaction, leading to strong attraction of H by the axial strain components of edge dislocations and by screw dislocations oriented along the critical 〈1 1 1〉 slip direction. We further find a H-concentration enhancement around dislocation cores, consistent with experimental observations. (paper)