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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 9: Microscopy and Tomography with X-ray Photons, Electrons, Ions and Positron
KFM 9.5: Talk
Wednesday, March 29, 2023, 10:20–10:40, POT 106
Formation and time dynamics of hydrogen-induced vacancies in nickel — •Maik Butterling1, Luca Chiari2, Masanori Fujinami2, Maciej Oskar Liedke1, Eric Hirschmann1, Ahmed Gamal Attallah1, and Andreas Wagner1 — 1Institute for Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — 2Department of Applied Chemistry and Biotechnology, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan
The formation of hydrogen-induced defects in nickel was investigated by positron annihilation lifetime spectroscopy and the time dynamics of those defects during room temperature aging was tracked with an unprecedented time resolution of the order of minutes using an ultrahigh-flux slow positron beam. Those measurements showed the formation of a large number of atomic vacancies simply by hydrogen addition at room temperature. It could be proved that they were monovacancy-level defects and that hydrogen was trapped and bound to those vacancies during the hydrogen charge. Room temperature aging, i.e. below the stage III temperature in Ni, and the concomitant hydrogen desorption induced the agglomeration of those monovacancies into large vacancy clusters which remained even after all the hydrogen had desorbed and hydrides had disappeared.
These results [1] constitute the first empirical evidence that vacancy-hydrogen complexes are induced in Ni only by hydrogen charging and demonstrate that hydrogen has a primary role in the formation and stabilization of vacancies even at room temperature.
[1] L. Chiari, et al., Acta Materialia 219(2021), 117264