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Lecture

New insights into plasticity at grain boundaries by nano- and micromechanics

Thursday (27.09.2018)
15:15 - 15:30 S1/01 - A1
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Nano- and micromechanical testing on focused ion beam (FIB) milled pillars is frequently used to study size effects in materials. It also allows for isolating the effect of individual interfaces, like grain- or phase-boundaries on the strength, which nowadays gives us a unique tool for justifying and quantifying well-established material models for various dislocation slip transfer mechanisms.

Our current work focusses on slip transfer mechanisms and its dependence on (i) grain boundary (GB) type, (ii) loading direction and (iii) atomistic structure at the interface. In situ methods are applied to investigate the transfer from individual dislocations through the GB (via TEM), the collective storage (via µLaue diffraction) and collective transmission behavior (via SEM). In the talk, we comprehensively present first results on slip transfer in copper bi-crystals. Four different GB types, all made from copper, will be presented and discussed: (i) High Angle GBs (HAGBs) acting as strong obstacle for dislocation slip transfer; (ii) HAGBs allowing for easy slip transfer and (iii) coherent sigma 3 twin-boundaries. The experimentally findings will be compared to well-established models and to recent MD simulations.

 

Speaker:
Dr. Christoph Kirchlechner
Max-Planck-Institut für Eisenforschung GmbH