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MM: Fachverband Metall- und Materialphysik
MM 44: Topical Session: Interface-dominated phenomena - Solutes at Interfaces II
MM 44.5: Vortrag
Mittwoch, 18. März 2020, 18:15–18:30, IFW A
Microscopic understanding of Zn diffusion in Fe grain boundaries. — •Michael Geier2, Martin Panholzer1, Martin Hoffmann1, Heiko Groiss2, Kurt Hingerl1, and Robert E. Zillich1 — 1Johannes Kepler University, Linz, Austria — 2Christian Doppler Laboratory for Nanoscale Phase Transformations, Center for Surface and Nanoanalytics, Johannes Kepler University, Linz, Austria
Zn coatings are widely used for corrosion protection of steel. However, Zn can lead to a weakening of steel grain boundaries during steel processing at higher temperatures. To investigate this liquid metal embrittlement in the presence of liquid zinc, the diffusing properties of a single Zn atom in Fe grain boundaries were studied using density functional theory which treat the Zn-Fe interactions very accurately. In our approach, we built a simple bcc Fe grain boundary or a dislocation in bcc Fe, and placed a Zn atom within both. With the nudged elastic band method we calculated the energy barrier which the Zn atom has to overcome for moving along the grain boundary or dislocation. Additionally we calculated with transition state theory and random walk theory the diffusion coefficient of the one dimensional diffusion of Zn along the grain boundary. Our results show that the Zn atom diffusion depends strongly on the type of lattice defect, i.e. grain boundary or dislocation. However, it turns out that the difference decreases when approaching melting temperature.