Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 19: Computational Materials Modelling IV - Finite Temperature
MM 19.4: Vortrag
Dienstag, 27. März 2012, 11:00–11:15, TC 006
Ab initio study of elasticity and phase transformations in Fe above the Curie temperature — Martin Friák1, •Alexander Udyansky1, David Holec2, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany — 2Montanuniversität Leoben, Leoben, Austria
Understanding and tailoring the thermodynamic and elastic properties of paramagnetic body-centered cubic iron (β-Fe) is fundamental for developing Fe-based materials operating at elevated temperatures. We have therefore studied β-Fe, modeled by an antiferromagnetic supercell, with the internal distribution of local magnetic moments having the special quasirandom structure (SQS). In contrast to previously suggested antiferromagnetic models that were found to be mechanically unstable with respect to tetragonal deformations, the proposed SQS supercell is stable. Using this approach the thermodynamic stability of β-Fe with respect to tetragonal and trigonal deformations has been studied. The corresponding total energies have been determined for a broad range of deformations and are compared with those calculated for other magnetic states. The calculated single-crystalline elastic constants are found to closely reproduce experimental data detected within the temperature range of β-Fe.