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MI: Fachverband Mikrosonden

MI 5: Quantitative Materialanalyse (mit KR)

MI 5.4: Vortrag

Dienstag, 12. März 2013, 10:45–11:00, H5

phase diagram of nano-hydride formation: consequences for hydrogen embrittlement — •Gerard Paul Leyson, Blazej Grabowski, Johann von Pezold, and Jörg Neugebauer — Max-Planck-Straße 1, 40237 Düsseldorf, Germany

Local hydride formation around dislocations induces stress-shielding effects and is the underlying mechanism for hydrogen-enhanced local plasticity (HELP). In this work, we present an analytic model for hydride formation around fcc Ni edge dislocations that takes input from atomistic calculations. The hydrogen-hydrogen interaction is modeled using information obtained from a semi-empirical embedded atom method (EAM) potential. Within this approach, the equilibrium concentration and the binding energies of hydrogen around the dislocation are self-consistently calculated. At 300K, local hydride formation is observed with bulk hydrogen concentrations on the order of ~500ppm, consistent previous studies [1]. The onset of nano-hydride formation and with it the activation of the HELP mechanism is predicted through a parametric study of the hydride size as a function of temperature and bulk hydrogen concentration.

[1] von Pezold J, Lymperakis L and Neugebeauer J. Acta Materialia 59 (2011), 2969-2980.