Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 60: Computational Materials Modelling IX - Interfaces and Boundaries

MM 60.5: Vortrag

Donnerstag, 29. März 2012, 18:15–18:30, TC 006

Hydrogen diffusion in Fe grain boundaries: A kinetic Monte Carlo study — •Yaojun A. Du¹, Jutta Rogal², and Ralf Drautz² — ¹Fakultät für Physik, Universität Duisburg-Essen, Lotharstraße 1, 47048 Duisburg, Germany — ²ICAMS, Ruhr-Universität Bochum, 44780 Bochum, Germany

Hydrogen embrittlement in iron and steels is a complex problem that is still not fully understood. Structural defects in the material such as vacancies, grain boundaries, and dislocations can trap hydrogen and a local accumulation of hydrogen at these defects can lead to a degradation of the materials properties. An important aspect in obtaining insight into hydrogen embrittlement on the atomistic level is to understand the diffusion of hydrogen in these materials.

In our study we employ kinetic Monte Carlo (kMC) simulations to investigate hydrogen diffusion in bcc iron including the effect of different microstructures. All input data to the kMC model, such as available sites, solution energies, and diffusion barriers are based on ab initio calculations. In particular we consider an idealised cubic grain structure exhibiting bulk and interface sites, an idealised layered structure and a more realistic model of the Σ 5 [001] (310) grain boundary in bcc-Fe. We find that hydrogen mainly diffuses within the interface region with an overall diffusivity that is lower than in pure bcc-Fe bulk. To describe the macroscopic diffusion behaviour we derive an analytic expression as a function of hydrogen concentration and temperature which is in excellent agreement with our numerical results.