Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 26: Poster Session
MM 26.51: Poster
Dienstag, 23. März 2010, 14:45–16:30, Poster C
Chemical trends of the solution enthalpy of hydrogen in 3d transition metals in dilute limit, derived from first principles — •Ugur Aydin1, Lars Ismer2, Tilmann Hickel1, and Jörg Neugebauer1 — 1Max-Planck Institut für Eisenforschung GmbH — 2University of California, Santa Barbara
Hydrogen embrittlement is a general phenomenon, which has already been observed in several transition metals and which is of high technological relevance. Despite many investigations of related mechanisms, a purely theoretical prediction how much a material of a certain chemical composition is affected by hydrogen embrittlement is still not possible. However, there is no doubt that the hydrogen solution enthalpy, ΔH, and its dependence on the crystal strain is a decisive criterion. We therefore performed a detailed ab initio investigation of the ΔH dependence on the band filling in 3d transition metals under comparable conditions. For this purpose, density functional theory within the GGA approximation was employed. Zero point vibrations have been taken into account using the Einstein model. The analysis revealed a universal dependence on the crystal lattice constant, with a material specific interplay of chemical and strain contributions. We compared our first principles findings with semi-empirical rules for the hydrogen solubility stated by Griessen et al. [PRB 38, 3690 (1988)] and confirmed that out of the parameters discussed there (electronic density, bandwidth of the d-band, atomic spacing) the distance of nearest neighbouring host atoms has the most systematic influence on ΔH.