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First-principles investigation of hydrogen trapping and diffusion at grain boundaries in nickel

: Stefano, D. di; Mrovec, M.; Elsässer, C.

Preprint urn:nbn:de:0011-n-3694794 (2.9 MByte PDF)
MD5 Fingerprint: df2424bc1478aae28fad1204dff113bc
Erstellt am: 25.07.2017

Acta Materialia 98 (2015), S.306-312
ISSN: 1359-6454
European Commission EC
FP7-NMP; 263335; MULTIHY
Zeitschriftenaufsatz, Elektronische Publikation
Fraunhofer IWM ()
hydrogen embrittlement; Nickel; grain boundary; diffusion; segregation

In this work, the interaction of hydrogen with high-angle GBs in nickel has been investigated by means of density functional theory simulations. Two distinct types of GBs have been considered: the Sigma 3 (1 1 1)[(1) over bar 1 0] with a close-packed interface structure and the Sigma 5(2 1 0)[0 0 1] with a less dense interface structure consisting of open structural units. Our calculations reveal that these two GBs have a markedly different interaction behavior with atomic hydrogen. The close-packed Sigma 3 GB neither traps H nor enhances its diffusion, but instead acts as a two-dimensional diffusion barrier. In contrast, the Sigma 5 GB provides numerous trapping sites for H within the open structural units as well as easy migration pathways for H diffusion along the GB plane that can enhance the H diffusivity by about two orders of magnitude compared to bulk Ni. The obtained results are analysed in detail and compared with available experimental and other theoretical data.