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MM: Fachverband Metall- und Materialphysik

MM 42: Mechanical Properties I

MM 42.1: Vortrag

Mittwoch, 18. März 2015, 15:45–16:00, TC 010

A first principles investigation of zinc induced embrittlement at grain boundaries in bcc iron — •Mira Todorova¹, Klaus-Dieter Bauer², Kurt Hingerl², and Jörg Neugebauer¹ — ¹Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany — ²Zentrum für Oberflächen- und Nanoanalytic, Universität Linz, Altenberger Str. 69, 4040 Linz, Austria

Using density-functional theory calculations we study the embrittling behaviour of liquid Zn in the Σ 3[111]60^∘ and the Σ 5[100]36.8^∘ symmetric tilt grain boundaries in bcc iron (ferrite). Investigating Zn induced changes in the energetics of the grain boundaries and their associated free surfaces we utilise both the canonical Griffith model and the grand canonical Rice-Wang formulation to evaluate the difference between the calculated grain boundary energies and the surface energies of their corresponding surfaces. We find that Zn wetting can reduce the cohesive strength of the interface by up to 40% and that the critical nominal bulk Zn concentration at which grain boundary weakening starts is almost two orders of magnitude lower in a grand-canonical model compared to the canonical case. The obtained results will be critically reviewed and discussed in the context of the embrittling behaviour of liquid zinc.

K.-D. Bauer, M. Todorova, K. Hingerl and J. Neugebauer, Acta Materialia (submitted).