Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 15: Poster Session

MM 15.14: Poster

Montag, 11. März 2013, 18:00–20:00, Poster E

Stacking faults in fcc Iron: The Influence of Magnetism — •Ivan Bleskov, Tilmann Hickel, and Jörg Neugebauer — Max-Planck-Institut für Eisenforschung GmbH, D-40237 Düsseldorf, Germany

The stacking fault energy is a critical parameter that defines the type of plasticity mechanism in austenitic high-Mn steels, which are characterized by a combination of enhanced formability and strength. A common concept for its description is the generalized stacking fault energy (γ-) surface, which describes the sliding of one part of a perfect crystal against the other. It provides the energy paths and barriers, which the system needs to overcome to form an intrinsic stacking fault (ISF). The goal of the present work is to study the influence of magnetism on the topology of the γ-surface. To avoid the influence of chemical effects, we have focused the investigation on pure fcc Fe. Density functional theory has been used for calculations of different magnetic (non-, ferro- antiferro-, and paramagnetic) structures. The paramagnetic state, which is closest to reality, was approximated by the disordered local moments (DLM) realized within the coherent potential approximation. Changing to magnetically ordered structures the γ-surface is strongly altered. The effects are stronger for ferro- than for antiferromagnetic configurations. The nonmagnetic γ-surface, however, is in the relevant region in very good agreement with DLM, and therefore may be used to reduce the complexity in future ISF calculations.