Journal
ACTA MATERIALIA
Volume 201, Issue -, Pages 23-35Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2020.09.048
Keywords
Hydrogen clustering; Metal; Stress; Modeling; Dislocation
Funding
- Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grants Program [NSERC RGPIN-2017-05187]
- McGill William Dawson Scholar Award
- National Key R and D Program of China [2018YFE0308102]
- National Natural Science Foundation of China [11735015, 51771185]
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Hydrogen (H) induced damage in metals has been a longstanding woe for many industrial applications. One form of such damage is linked to H clustering, for which the atomic origin remains contended, particularly for non-hydride forming metals. In this work, we systematically studied H clustering behavior in bcc metals represented by W, Fe, Mo, and Cr, combining first-principles calculations, atomistic and Monte Carlo simulations. H clustering has been shown to be energetically favorable, and can be strongly facilitated by anisotropic stress field, dominated by the tensile component along one of the < 001 > crystalline directions. We showed that the stress effect can be well predicted by the continuum model based on H formation volume tensor, and that H clustering is thermodynamically possible at edge dislocations, evidenced by nanohydride formation at rather low levels of H concentration. Moreover, anisotropy in the stress effect is well reflected in nanohydride morphology around dislocations, with nanohydride growth occurring in the form of thin platelet structures that maximize one < 001 > tension. In particular, the < 001 > type edge dislocation, with the < 001 > tensile component maximized, has been shown to be highly effective in facilitating H aggregation, thus expected to play an important role in H clustering in bcc metals, in close agreement with recent experimental observations. This work explicitly and quantitatively clarifies the anisotropic nature of stress effect on H energetics and H clustering behaviors, offering mechanistic insights critical towards understanding H-induced damages in metals. Crown Copyright (C) 2020 Published by Elsevier Ltd on behalf of Acta Materialia Inc. All rights reserved.
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