Regensburg 2025 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 11: Topical Session: Defects of Defects
MM 11.1: Topical Talk
Dienstag, 18. März 2025, 10:15–10:45, H10
The role of disconnections in the shear-migration coupling of grain boundaries — •Marc Legros1, Armin Rajabzadeh1, Romain Gautier2, Nicolas Combe1, and Frédéric Mompiou1 — 1CEMES-CNRS, 29 rue Jeanne Marvig, 31055, Toulouse, France — 2UMET, Université de Lille, Cité scientifique, 59655 Villeneuve d'Ascq
Grain-boundary (GB)-based plasticity is an alternative to classical, dislocation-based deformation. It is supposed to play a significant role in nanocrystalline metals (d<100 nm) for example, that contain a large proportion of GBs but virtually no dislocations. Among all the mechanisms potentially able to generate a permanent (plastic) deformation, the dominant one is the so-called shear-migration coupling. Despite a recent increase in simulations studies, its experimental characterization remains very scarce. Aside from experimental obstacles, the problem is very vast as real grain boundaries possess at least 5 degrees of freedom and contains a potentially infinite number of disconnections, a specific defect that combines step and dislocation characters.
Using both in-situ TEM experiments and molecular dynamic simulations (NEB Nudge Elastic Band), we have shown that shear-migration coupling involves the displacement of these disconnections. As dislocations in the crystal, the properties of these disconnections seem to guide the coupling mechanism of migrating grain boundaries. The overarching question becomes whether we should still consider a given GB as a crystalline defect or a network of its own, which mechanical properties (mobility, shear coupling) are governed by its nature or by its defects?
Keywords: Grain boundaries; Plasticity; Disconnection; Shear-migration coupling