Irreversible evolution of dislocation pile-ups during cyclic microcantilever bending
| Autor: | Ugi, Dávid, Zoller, Kolja, Lukács, Kolos, Fogarassy, Zsolt, Groma, István, Kalácska, Szilvia, Schulz, Katrin, Ispánovity, Péter Dusán |
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| Rok vydání: | 2023 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | In metals geometrically necessary dislocations (GNDs) are generated primarily to accommodate strain gradients and they play a key role in the Bauschinger effect, strain hardening, micron-scale size effects and fatigue. During bending large strain gradients naturally emerge which makes this deformation mode exceptionally suitable to study the evolution of GNDs. Here we present bi-directional bending experiment of a Cu single crystalline microcantilever with in situ characterisation of the dislocation microstructure in terms of high-resolution electron backscatter diffraction (HR-EBSD). The experiments are complemented with dislocation density modelling to provide physical understanding of the collective dislocation phenomena. We find that dislocation pile-ups form around the neutral zone during initial bending, however, these do not dissolve upon reversed loading, rather they contribute to the development of a much more complex GND dominated microstructure. This irreversible process is analysed in detail in terms of the involved Burgers vectors and slip systems to provide an in-depth explanation of the Bauschinger-effect and strain hardening at this scale. We conclude that the most dominant role in this behaviour is played by short-range dislocation interactions. Comment: manuscript submitted to Acta Materialia |
| Databáze: | arXiv |
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