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MM: Fachverband Metall- und Materialphysik

MM 12: Computational Materials Modelling - Mechanical Properties

MM 12.5: Vortrag

Montag, 11. März 2013, 16:45–17:00, H24

First-principles calculations of the key atomistic parameters related to hydrogen embrittlement in FeMn — •Aurab Chakrabarty, Johann von Pezold, Robert Spatschek, Tilmann Hickel, and Joerg Neugebauer — Max-Planck Institute for Iron Research, Duesseldorf, Germany

Hydrogen embrittlement in high-manganese steels has been in the centre of attention for automotive applications. It is difficult to perceive the role of hydrogen of these steels solely from experiments. However, key atomistic parameters such as H-H interaction, elastic constants, solution energies and stacking fault energies can be systematically determined from first-principles calculations. They can be used to create a fully ab-initio based continuum scale simulation and validate commonly assumed assumptions of H-segregation on stacking faults, crack-tips and cleavages and eventually to understand phenomena such as HELP (hydrogen enhanced local plasticity).

In this work we apply density functional theory to investigate the role of hydrogen in FeMn. Starting with the crystal and magnetic structure for H-interstitials, we calculated the hydrogen solution energy in a hydride phase and H-H interactions in Fe and Mn in order to investigate the possibility of hydrogen congregation. The energetic preferences of the interstitial sites for a hydrogen atom in Fe-Mn alloy based on the number of Fe/Mn neighbours, have been determined. These parameters, including their chemical and elastic contributions were analyzed in order to understand the nature of the defect and implications for alloys those are less sensitive to H-embrittlement.