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Depinning transition of dislocation assemblies: Pileups and low-angle grain boundaries
Moretti, Paolo; Miguel López, María del Carmen; Zaiser, Michael; Zapperi, Stefano
Universitat de Barcelona
We investigate the depinning transition occurring in dislocation assemblies. In particular, we consider the cases of regularly spaced pileups and low-angle grain boundaries interacting with a disordered stress landscape provided by solute atoms, or by other immobile dislocations present in nonactive slip systems. Using linear elasticity, we compute the stress originated by small deformations of these assemblies and the corresponding energy cost in two and three dimensions. Contrary to the case of isolated dislocation lines, which are usually approximated as elastic strings with an effective line tension, the deformations of a dislocation assembly cannot be described by local elastic interactions with a constant tension or stiffness. A nonlocal elastic kernel results as a consequence of long-range interactions between dislocations. In light of this result, we revise statistical depinning theories of dislocation assemblies and compare the theoretical results with numerical simulations and experimental data.
2010-05-04
Matèria condensada
Regla de les fases i equilibri
Propietats mecàniques
Propietats acústiques
Cristal·lografia
Condensed matter
Equations of state
Phase rule and equilibrium
Mechanical properties
Acoustic properties
Crystallography
(c) The American Physical Society, 2004
Article
The American Physical Society
         

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