Berlin 2015 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 9: Hydrogen in metals II: Multiscale simulations

MM 9.3: Vortrag

Montag, 16. März 2015, 12:30–12:45, TC 006

Scale bridging modelling of hydride formation — •Robert Spatschek, Georgia Gobbi, Claas Hüter, Aurab Chakrabarty, Ugur Aydin, and Jörg Neugebauer — Max-Planck Institut für Eisenforschung, Düsseldorf

We investigate phase separation in the bulk and at surfaces and find a reduction of the solubility limit near free surfaces due to elastic coherency effects. This mechanism favours nucleation from free surfaces even in the absence of external stresses. We apply the theory to hydride formation in nickel, iron and niobium and obtain a reduction of the solubility limit by up to two orders of magnitude at room temperature at free surfaces. This leads to a blurring of the distinction between hydride-forming and non-hydride-forming metals. Near stiff substrates, in contrast, the solubility limit is increased, in agreement with experimental observations. These effects are concisely expressed through a solubility modification factor, which transparently expresses the long-ranged elastic effects in a terminology accessible e.g. to ab initio calculations and experiments. The predictions are confirmed by Cahn-Hilliard simulations on the continuum level.