Ab initio parametrised model of strain-dependent solubility of H in alpha-iron

TL;DR

This paper develops an ab initio parametrized model to predict how hydrogen solubility in alpha-iron varies with different types of elastic strain, including complex dislocation fields.

Contribution

It introduces a simple, ab initio-derived model for hydrogen solubility under various strains, enabling predictions of H behavior near dislocations in iron.

Findings

Hydrogen shows strong attraction to axial strain components of dislocations.

H concentration is enhanced around dislocation cores, matching experimental data.

The model accurately predicts H solubility in spatially-varying elastic strain fields.

Abstract

The calculated effects of interstitial hydrogen on the elastic properties of alpha-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 parametrised 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 < 111 > slip direction. We further find a H concentration enhancement around dislocation cores, consistent with experimental observations.