Hydrogen segregation near a crack tip in nickel

Andreas Drexler, Shuang He, Reinhard Pippan, Lorenz Romaner, V.I. Razumovskiy, Werner Ecker

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The effect of severe elastic straining of interstitial lattice sites in front of a crack tip in nickel is investigated. There the volumetric strains can reach values close to the theoretical limit of around 20%. Segregation energies of volumetrically strained octahedral sites were calculated by means of the density functional theory (DFT) and were compared with the segregation energies of hydrogen trapped at the free surface and other microstructural defect sites. The calculations revealed a strong effect of volumetric straining on hydrogen segregation in the first atomic layers ahead the crack tip, which is comparable to hydrogen segregation at grain boundaries or vacancies. According to the calculations, the hydrogen distribution in the process zone is strongly inhomogenous with full occupation of, both, free surface sites and volumetric strained sites in the first atomic layers in front of the crack tip.

Original languageEnglish
Article number113697
Number of pages5
JournalScripta materialia
Issue number15 March
Early online date5 Jan 2021
Publication statusPublished - 15 Mar 2021

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