Dresden 2017 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 8: Topical session: Interface-Controlled Microstructures: Mechanical Properties and Mechano-Chemical Coupling - Segregation and Embrittlement II

MM 8.6: Vortrag

Montag, 20. März 2017, 13:00–13:15, BAR 205

Silver segregation induced nanofaceting of an asymmetric tilt grain boundary in copper — •Nicolas J. Peter, Christian H. Liebscher, Raheleh Hadian, Blazej Grabowski, Christoph Kirchlechner, and Gerhard Dehm — Max-Planck Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany

Grain boundary faceting is a thermally activated process. It can be suppressed on experimental time scales depending on temperature and driving force. We show here that chemistry can be used to intentionally trigger faceting.

The present study investigates the segregation of Ag to an asymmetric tilt boundary in Cu. Aberration-corrected high-resolution scanning transmission electron microscopy reveals that annealing the Ag coated bicrystal at 800°C for 120 h results in the formation of nanometer-sized, regularly spaced, symmetric Sigma 5 (210) segments within the overall asymmetric boundary. We confirm that reference samples without Ag, annealed under the same conditions, show no thermally activated faceting, even down to the atomic level.

Our observations oppose an anticipated trend to form coarse facets or change the overall boundary plane orientation to lower energy Sigma 5 (210) or (310) planes. Atomistic simulations on specifically chosen reference boundaries support the experimental observations and reveal the atomistic mechanisms of the chemically induced nanofaceting.

Migration paths and atomic column occupancies are extracted over time to allow for a first quantification approach of such a system, thereby showing the stability of the induced Ag containing nanofacets.