Dresden 2014 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 38: Structural materials
MM 38.1: Talk
Wednesday, April 2, 2014, 10:15–10:30, IFW B
Relation between thermodynamic stability and stacking fault energies in Mg alloys: An ab-initio study — •Zongrui Pei1,2, Li-Fang Zhu1, Martin Friák1, Stefanie Sandlöbes1, Stefan Zaefferer1, Bob Svendsen1,2,3, Dierk Raabe1, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany — 2Aachen Institute for Advanced Study in Computational Engineering Science (AICES), RWTH Aachen University, Germany — 3Faculty of Georesources and Materials Engineering, RWTH Aachen University, Germany
Pure magnesium and most commercial wrought magnesium alloys exhibit a low room temperature ductility which can be significantly increased by the addition of Y or rare earth (RE) elements (Acta Mater. 59 (2011) 429). Understanding the mechanisms causing this ductility enhancement on an atomistic and electronic-structure level would provide a systematic approach to identify alternative favorable solutes. Therefore, in order to obtain a deeper insight into the mechanisms active in the Mg-Y and Mg-RE alloys, an ab-initio study of the compositional dependence of intrinsic stacking fault (ISF) energies have been performed. Employing density functional theory (DFT) calculations, the ISF energies have been determined within the Axial Next-Nearest-Neighbour Ising (ANNNI) model. An in-depth analysis of the theoretical data shows reduced ISF energies as a direct consequence of the dramatically reduced thermodynamic stability of hexagonal Mg-Y solid solutions when the Y concentration approaches its solubility limit in Mg (Acta Mater. 60 (2012) 3011).