CUED Publications database

Grand canonical approach to modeling hydrogen trapping at vacancies in alpha-Fe

Davidson, ERM and Daff, T and Csanyi, G and Finnis, MW (2020) Grand canonical approach to modeling hydrogen trapping at vacancies in alpha-Fe. PHYSICAL REVIEW MATERIALS, 4. ISSN 2475-9953

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Abstract

Vacancies in iron are hydrogen traps, important in the understanding of hydrogen embrittlement of steel. We present a grand canonical approach to computing the trap occupancy as a function of both temperature and hydrogen concentration from practically zero to super-saturation. Our method couples a purpose-made machine-learned H-Fe potential, which enables rapid sampling with near density functional theory accuracy, with a statistical mechanical calculation of the trap occu- pancy using the technique of nested sampling. In contrast to the conventional assumption (based on Oriani theory) that at industrially relevant hydrogen concentrations and ambient conditions vacancy traps are are fully occupied, we find that vacancy traps are less than fully occupied under these conditions, necessitating a reevaluation of how we think about “mobile hydrogen” in iron and steel.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div C > Applied Mechanics
Depositing User: Cron Job
Date Deposited: 23 Jul 2020 08:08
Last Modified: 02 Mar 2021 07:04
DOI: 10.1103/PhysRevMaterials.4.063804