Berlin 2008 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 41: Poster SYM Hydrogen in Materials: New Developments

MM 41.18: Poster

Donnerstag, 28. Februar 2008, 18:00–20:00, Poster B

Hydrogen in V-8at%Fe single-layered films and Fe/V multi-layered films — •Ryota Gemma, Talaat Al-Kassab, Reiner Kirchheim, and Astrid Pundt — Institut fuer Materialphysik, Friedrich-Hund-Platz 1, D-37077, Goettingen, Germany

The influence of out-of-plane lattice parameter a₀ of V layer on the plateau slope of electromotive force (EMF) curves of V-8at%Fe films and Fe/V multi-layered films was investigated by applying in-situ XRD and in-situ stress measurements equipped with electrochemical hydrogen loading set up. For the films with small a₀, the plateau slope and hydrogen-induced stress were found to be larger than those with larger a₀. This trend can be qualitatively understood if we consider that hydrogen atoms predominantly occupy O_z sites in vanadium hydride phase, unlikely for the materials with isotropic site occupation as Pd. The deuterium distribution in the same kind of (110) films was also investigated by atom probe tomographic analysis (APT). The depth profile of the Fe/V films showed D atoms concentrated in V layers, as expected from the fact that V has bigger enthalpy for hydrogenation than that of Fe. However, the D concentration was not homogeneous in a V layer and far below the expected value from EMF curve. A similar phenomenon was found also for V-8at%Fe single-layered film. The results will be discussed in terms of difference in the microstructure and initial stress of the films.