Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 28: Topical Session Theory meets Experiment I - Intermetallics and Steels

MM 28.4: Vortrag

Mittwoch, 28. März 2012, 11:15–11:30, TC 006

Understanding H-induced failure mechanisms in metallic alloys: The role of attractive H-H interactions in nano-precipitate formation — •Johann von Pezold, Alexander Udyansky, and Joerg Neugebauer — Max Planck Institut fuer Eisenforschung GmbH, Duesseldorf

Attractive H-H interactions have recently been shown to induce the formation of local hydride precipitates even in non-hydride forming matrices, such as Ni [1]. The formation of these nano-hydrides in the strain field of lattice defects such as crack tips and dislocations has been correlated to the long-standing problem of hydrogen embrittlement in these metals. In this study we systematically investigate H-H interactions in a range of fcc matrices, including Ca, Mn, Fe, Co, Ni, Al and Pd, using density functional theory. While the interaction between H atoms in first nearest neighbour interstitial sites is generally attractive, the nature of this interaction is strongly system and site dependent. Hence, the interaction between octahedral sites is predominantly of elastic nature, while interactions between tetrahedral sites exhibit a significant chemical contribution. Based on this study the formation of nano-hydrides in fcc metals will be critically discussed.

[1] J. von Pezold, L. Lymperakis and J. Neugebauer, Acta Mat. 59, 2969 (2011).