Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 53: Microstructure and Phase Transformations II
MM 53.4: Vortrag
Donnerstag, 10. März 2016, 12:30–12:45, H39
Zener ordering of interstitials in a bcc host lattice: Interplay between short- and long-range interactions — •Xie Zhang1, Tilmann Hickel1, Jutta Rogal2, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung GmbH, 40237 Düessldorf, Germany — 2Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universität Bochum, 44780 Bochum, Germany
The octahedral interstitial sites in a bcc lattice can be categorized into three sublattices that can be occupied with interstitials and that are characterized by the corresponding tetragonal deformation variants ([100], [010] and [001]). Even in an external stress-free system, the interstitials energetically prefer to occupy only one of the three sublattices below a critical temperature. This preference is triggered by the interactions between the interstitials and termed Zener ordering. Although it was proposed by Zener more than half a century ago, direct proofs from atomistic simulations have been, however, rarely reported so far, which even resulted in a debate on the validity of such ordering recently. Hence, in this work, we employ atomistic simulations to directly investigate the interplay between long-range strain induced and short-range chemical interactions. It is found that a homogenized distribution of interstitials within one octahedral sublattice is crucial, and ensures that the short- and long-range interactions are minimized simultaneously. These insights help to understand self-induced collective ordering of interstitials within a bcc host lattice which is a key mechanism to harden steels.