Regensburg 2010 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 12: Topical Session Designing Innovative Structural Materials and Steels III
MM 12.4: Vortrag
Montag, 22. März 2010, 15:30–15:45, H4
Atomistic studies of dislocations in α-iron using bond-order potential — •Matous Mrovec1,2, Christian Elsässer1,2, and Peter Gumbsch1,2 — 1Fraunhofer-Institut für Werkstoffmechanik IWM, Freiburg, Germany — 2IZBS, Universität Karlsruhe, Karlsruhe, Germany
Macroscopic plastic behavior is closely linked to properties of dislocations at the nanometer scale. Direct experimental observations of the dislocation core region and of its changes during dislocation motion are unfortunately impossible and better understanding of these phenomena can be obtained only with the help of atomistic simulations. Recent atomistic studies of dislocations in iron have provided however very different outcomes, both in terms of atomic structures and energetics. The most likely reason of these large differences is a lack of reliable interatomic potentials, which would be able to describe adequately the atomic bonding and magnetic interactions in iron.
In the present work we present studies of dislocations in α-iron using a bond-order potential, which is based on a tight-binding bond representation. The model is able to capture the directional character of bonds present in transition metals and includes a description of magnetic effects within the Stoner model of itinerant magnetism. We will compare results of our simulations with available first-principles predictions as well as with predictions of other empirical interatomic potentials and discuss underlying causes of the differences.