Berlin 2015 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 33: Structural Materials I: Phase Stability and Mechanical Properties
MM 33.4: Talk
Wednesday, March 18, 2015, 11:00–11:15, TC 010
From generalized stacking fault energies to dislocation cores: impact of solutes on the Peierls stress in magnesium — •Zongrui Pei1,2, Martin Friák3,1,2, and Jörg Neugebauer1 — 11Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany — 2Aachen Institute for Advanced Study in Computational Engineering Science (AICES), RWTH Aachen University, Aachen, Germany — 3Institute of Physics of Materials of the Academy of Sciences of the Czech Republic, v.v.i, Brno, Czech Republic
Using ab initio calculations and Fourier transform we analyze a basal plane gamma surface in pure Mg and show that the knowledge of energies of only three specific points is sufficient to accurately predict the core structure of <a> dislocations. This finding greatly reduces the computational costs related to the Peierls-Nabarro (PN) model and allows for a high-throughput application of the PN model to dislocation cores in Mg alloys. We employ our approach to study Mg binary alloys containing 9 rare-earth (RE) and 11 other solutes that crystallize in either hexagonal close-packed (hcp) or double hcp (dhcp) structures. Based on the calculated core structures of these 20 Mg alloys, solutes are divided into three groups. The group consisting of Co, Os, Re, Ru, Tc and Ti shows more compact core structures and larger Peierls stress than pure Mg, the group including Be, Hf, Tl, Zn, Zr and Sc (the only RE element in this group) changes both the core widths and Peierls stresses moderately. The third group containing the other RE elements extend the core width from 9b-19b, and the Peierls stresses are generally very low, which shows a solute solution softening trend.