Three mechanisms of hydrogen-induced dislocation pinning in tungsten

Y. Li, T.W. Morgan, Dmitry Terentyev, Audrey Favache, Marius Wirtz, J.P.M. Hoefnagels, J.A.W. van Dommelen, Gregory De Temmerman, Kim Verbeken, M.G.D. Geers

    Research outputpeer-review


    The high-flux deuterium plasma impinging a divertor degrades the long-term thermo-mechanical performance of its tungsten plasma-facing components. A prime actor in this is hydrogen embrittlement, a degradation mechanism that involves the interactions between hydrogen and dislocations, the primary carriers of plasticity. Measuring such nanoscale interactions is still very challenging, which limits our understanding. Here, we demonstrate an experimental approach that combines thermal desorption spectroscopy (TDS) and nanoindentation, allowing to investigate the effect of hydrogen on the dislocation mobility in tungsten. Dislocation mobility was found to be reduced after deuterium injection, which is manifested as a ‘pop-in’ in the indentation stress-strain curve, with an average activation stress for dislocation mobility that was more than doubled. All experimental results can be confidently explained, in conjunction with experimental and numerical literature findings, by the simultaneous activation of three mechanisms responsible for dislocation pinning:(i) hydrogen trapping at pre-existing dislocations, (ii) hydrogen-induced vacancies, and (iii) hydrogen-stabilized vacancies, contributing respectively 38%, 52%, and 34% to the extra activation stress. These mechanisms are considered to be essential for the proper understanding and modeling of hydrogen embrittlement in tungsten.
    Original languageEnglish
    Article number086015
    Pages (from-to)1-11
    Number of pages11
    JournalNuclear Fusion
    StatePublished - 15 Jul 2020

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