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MM: Fachverband Metall- und Materialphysik

MM 6: Interface Controlled Properties, Nanomaterials and Microstructure Design I

MM 6.4: Vortrag

Montag, 18. März 2024, 11:00–11:15, C 230

Exploring the links between local interface chemistry and mechanics using in situ micromechanical testing — •James P. Best — Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, D-40237 Düsseldorf, Germany

The mechanisms governing dislocation plasticity and fracture at the smallest scales is critically linked to chemistry, in particular at defects, in dictating material behaviour. This has been demonstrated using in situ electron microscopy testing of, for example, copper and tungsten containing trace impurities at grain boundaries. For the study of recrystallised tungsten, in situ microcantilever testing coupled with atom probe tomography provided insights into the effects of impurity segregation on the toughness by placing the notch directly at grain boundaries. For both as-received material and single-crystalline recrystallised tungsten, plasticity was accumulated before failure through ductile crack tip tearing. In contrast, the toughness at grain boundaries dropped sharply, regardless of grain boundary misorientation or grain orientation. Atom probe analysis of the grain boundaries showed segregation of phosphorous to the recrystallised interfaces. Atomistic simulations of a model Σ7 tungsten grain boundary containing phosphorous confirms a significant embrittlement along the decorated boundary. By elucidating such local chemical effects, we aim to pave the way for the design of materials with enhanced strength and toughness.

Keywords: Microcantilever; Fracture toughness; Grain boundaries; Segregation; Tungsten