Interatomic Fe-H potential for irradiation and embrittlement simulations

TL;DR

This paper introduces a new interatomic Fe-H potential based on density-functional theory for large-scale molecular dynamics simulations, enabling studies of hydrogen effects in iron and steel.

Contribution

It develops a novel analytical Fe-H potential in the Tersoff-Brenner formalism, compatible with existing steel potentials, for simulating hydrogen interactions in iron.

Findings

Hydrogen softens iron in simulations.

Potential applicable to bulk Fe and grain boundary systems.

Enables modeling of hydrogen embrittlement effects.

Abstract

The behavior of hydrogen in iron and iron alloys is of interest in many fields of physics and materials science. To enable large-scale molecular dynamics simulations of systems with Fe-H interactions, we develop, based on density-functional theory calculations, an interatomic Fe-H potential in the Tersoff-Brenner formalism. The obtained analytical potential is suitable for simulations of H in bulk Fe as well as for modeling small FeH molecules, and it can be directly combined with our previously constructed potential for the stainless steel Fe-Cr-C system. This will allow simulations of, e.g., hydrocarbon molecule chemistry on steel surfaces. In the current work, we apply the potential to simulating hydrogen-induced embrittlement in monocrystalline bulk Fe and in an Fe bicrystal with a grain boundary. In both cases, hydrogen is found to soften the material.