title: Avalanches in 2D dislocation systems: plastic yielding is not depinning.
abstract: We study the properties of strain bursts (dislocation avalanches) occurring in two-dimensional discrete dislocation dynamics models under quasistatic stress-controlled loading. Contrary to previous suggestions, the avalanche statistics differ fundamentally from predictions obtained for the depinning of elastic manifolds in quenched random media. Instead, we find an exponent τ=1 of the power-law distribution of slip or released energy, with a cutoff that increases exponentially with the applied stress and diverges with system size at all stresses. These observations demonstrate that the avalanche dynamics of 2D dislocation systems is scale-free at every applied stress and, therefore, cannot be envisaged in terms of critical behavior associated with a depinning transition.
authors: Department of Materials Physics, Eötvös University Budapest, H-1117 Budapest, Pázmány Péter Sétány 1/a, Hungary.
authors: Péter Dusán
authors: PD
authors: Ispánovity
authors: COMP Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 11100, FIN-00076 Aalto, Espoo, Finland.
authors: Lasse
authors: L
authors: Laurson
authors: Institute of Materials Simulation, Department of Materials Science, University of Erlangen-Nürnberg, Dr.-Mack-Strasse 77, 90762 Fürth, Germany.
authors: Michael
authors: M
authors: Zaiser
authors: Department of Materials Physics, Eötvös University Budapest, H-1117 Budapest, Pázmány Péter Sétány 1/a, Hungary.
authors: István
authors: I
authors: Groma
authors: CNR-IENI, Via R. Cozzi 53, 20125 Milano, Italy and ISI Foundation, Via Alassio 11/C, 10126 Torino, Italy.
authors: Stefano
authors: S
authors: Zapperi
authors: COMP Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 11100, FIN-00076 Aalto, Espoo, Finland.
authors: Mikko J
authors: MJ
authors: Alava