Regensburg 2022 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 3: Microstructures and Phase Transformations: Metals & Alloys

MM 3.5: Vortrag

Montag, 5. September 2022, 11:15–11:30, H45

Atomic-scale observation of silver segregation in a high angle grain boundary in copper — •Lena Frommeyer, Tobias Brink, Gerhard Dehm, and Christian Liebscher — Max-Planck-Str. 1, 40213 Düsseldorf

Although it is well recognized that segregation to grain boundaries (GBs) influences mechanical and electrical properties of materials, the impact of segregation on individual GB phases is poorly understood on the atomic level. Thermodynamic models are established to describe equilibrium segregation, but the atomistic origins and direct observation of solute segregation inside the GB core structure are seldomly investigated since high resolution imaging and spectroscopy are required.

Lately, we were able to resolve the atomic structure of a symmetric Σ 37c <111> {3 4 7} tilt GB in a Cu thin film using aberration-corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). By depositing a 100 nm thin Ag layer on top of our 2 µm-thick Cu thin film and subsequent annealing at 600^∘C, we could investigate the effect of Ag segregation on these GBs. Interestingly, the structure of the GB remains unchanged. Ag atoms solely substitute specific sites in the GB. If the Ag content in the GB is increased, one atomic column in the GB structure is filled up first, followed by four other columns. A combination of atomic resolution energy dispersive X-ray spectrometry, HAADF-STEM experiments and atomistic simulations were used to explore the underlying mechanisms leading to the observed Ag segregation pattern.