title: Intermittent dislocation density fluctuations in crystal plasticity from a phase-field crystal model.
abstract: Plastic deformation mediated by collective dislocation dynamics is investigated in the two-dimensional phase-field crystal model of sheared single crystals. We find that intermittent fluctuations in the dislocation population number accompany bursts in the plastic strain-rate fluctuations. Dislocation number fluctuations exhibit a power-law spectral density 1/f2 at high frequencies f. The probability distribution of number fluctuations becomes bimodal at low driving rates corresponding to a scenario where low density of defects alternates at irregular times with high populations of defects. We propose a simple stochastic model of dislocation reaction kinetics that is able to capture these statistical properties of the dislocation density fluctuations as a function of shear rate.
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark.
authors.forename: Jens M
authors.initials: JM
authors.lastname: Tarp
authors.affiliation: Department of Physics, Physics of Geological Processes, University of Oslo, Post Office 1048 Blindern, 0316 Oslo Norway.
authors.forename: Luiza
authors.initials: L
authors.lastname: Angheluta
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen, Denmark.
authors.forename: Joachim
authors.initials: J
authors.lastname: Mathiesen
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign, Loomis Laboratory of Physics, 1110 West Green Street, Urbana, Illinois 61801-3080, USA.
authors.forename: Nigel
authors.initials: N
authors.lastname: Goldenfeld