Dresden 2014 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 18: Poster Session

MM 18.36: Poster

Montag, 31. März 2014, 18:00–20:00, P4

Waiting time statistics indicating crossover from 3D uncorrelated nano shear bands to cooperative shear motion — Jon-Olaf Krisponeit, •Sebastian Pitikaris, Karina E. Avila, Stefan Küchemann, Antje Krüger und Konrad Samwer — I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

We investigated the post-elastic creep deformation of Pd_77.5Cu₆Si_16.5 metallic glas ribbons via Dynamical Mechanical Analysis, i.e. we recorded its strain response over time after exerting a uniaxial stress jump. Macroscopically, one observes a smooth strain curve comprising of elastic, anelastic and plastic contributions. On a finer scale, however, the creep curve is made up of steplike jumps rather than proceeding continuously. We approach the statistical properties of the underlying slip events using a novel waiting time analysis. These show a power law distribution similar to those observed for other systems exhibiting avalanche dynamics e.g. Barkhausen noise or fracture in crystals. In long-time experiments we observed a crossover between two distinct power law regimes. We ascribe the first regime to the stress-assisted formation of 3D independent avalanches of shear transformation zones, the fundamental microscopic unit of deformation. The transition to a second power-law regime indicates the onset of cooperative 2D nano shear band motion. We acknowledge financial support for this work by DFG via SFB 602 and FOR 1394 and the German-Israeli Foundation.