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MM: Fachverband Metall- und Materialphysik

MM 26: Interface Controlled Properties and Nanomaterials: Grain Boundaries and Stability, Spectroscopy and Interatomic Potentials

MM 26.1: Vortrag

Mittwoch, 29. März 2023, 10:15–10:30, SCH A 216

Grain-boundary segregation effects on bicrystal Cu pillar compression — •Tobias Brink, Mohammed Kamran Bhat, James Best, and Gerhard Dehm — Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf

It is well known that segregation to grain boundaries (GBs) can modify the mechanical properties of metals, leading for example to improved strength, but also to detrimental effects like embrittlement. Despite this, the nanoscale mechanisms of these changes are currently not fully understood. Here, we present the results of atomistic computer simulations of bicrystalline Cu pillar compression and corresponding micromechanics experiments. The experiments show that Ag segregation to the GB increases the yield stress of the pillars, but only slip traces observed post mortem hint towards the mechanisms. We prepared segregated GB structures with combined molecular dynamics/Monte-Carlo simulations by matching the resulting excess Ag concentration to atom probe tomography results. The virtual nanopillars were cut from this material and varying amounts of dislocation loops were inserted in order to model the pre-existing dislocation networks in the experiment. Switching the atomic types of the segregants between Ag and Cu allowed us to model the exact same pillar and dislocation network with and without segregation, thereby enabling an investigation of the mechanisms underlying the experimentally observed strengthening.

Acknowledgment: This result is part of a project that has received funding from the ERC under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 787446).