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MM: Fachverband Metall- und Materialphysik

MM 30: Functional Materials III

MM 30.2: Vortrag

Mittwoch, 28. März 2012, 10:30–10:45, H 0106

Scale Bridging Modeling of Hydrogen Embrittlement — •Dominique Korbmacher, Claas Hüter, Johann von Pezold, and Robert Spatschek — Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany

Hydrogen is known to embrittle many metals and steels, resulting in the premature failure of these materials. As a prototype of such a material we investigate nickel, which does not form hydrides under standard conditions of temperature and pressure. However, the attractive hydrogen-hydrogen interactions within the metal matrix have been shown to induce the formation of nano-hydrides in distorted regions of the lattice (crack tips or dislocations) even at only moderately enhanced hydrogen chemical potentials. We perform atomistic Monte-Carlo simulations to investigate the formation of the hydride phase as a function of the hydrogen chemical potential and use these data to parametrise a thermodynamic model with special attention to the role of elastic effects, which drastically influence the behavior in the two-phase region. The results of this analysis are then used in mesoscale simulations for the formation of hydride zones around crack tips. To this end we simulate the diffusive flux of hydrogen towards the tensile regions of a crack, and investigate the growth of the hydride zone and its steady state size depending on the stress intensity factor and the hydrogen supply. The results are in agreement with analytical scaling relations.