A grand canonical approach for modelling hydrogen trapping at vacancies in alpha-Fe
File(s)
Supporting information
Accepted version
Author(s)
Finnis, MW
Csanyi, G
Daff, T
Davidson, ERM
Type
Journal Article
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 supersaturation. 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 occupancy 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.
Date Issued
2020-06-01
Date Acceptance
2020-05-14
Citation
Physical Review Materials, 2020, 4 (6)
ISSN
2475-9953
Publisher
American Physical Society
Journal / Book Title
Physical Review Materials
Volume
4
Issue
6
Copyright Statement
©2020 American Physical Society.
Sponsor
Engineering & Physical Science Research Council (E
Engineering & Physical Science Research Council (EPSRC)
Grant Number
EP/L014742/1
EP/P023118/1
Subjects
Science & Technology
Technology
Materials Science, Multidisciplinary
Materials Science
DIFFUSION
EFFICIENT
FAILURE
STEELS
NI
Publication Status
Published
Article Number
063804
Date Publish Online
2020-06-22