Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 62: Topical Session: Fundamentals of Fracture - Stochastic Aspects

MM 62.5: Vortrag

Donnerstag, 14. März 2013, 18:30–18:45, H4

The low temperature deformation properties of thermally active bulk metallic glasses — •Peter Derlet — Condensed Matter Theory Group, Paul Scherrer Institut, Switzerland

Despite significant atomic-scale heterogeneity, bulk metallic glasses well below their glass transition temperature exhibit a sharp transition to plasticity with a reproducible yield stress. Under tension, limited ductility is observed with the materials often exhibiting brittle fracture. Because of the high reproducibility of the yield stress such mechanical failure is not flaw based (as in a ceramic) but rather an intrinsic property of the structural glass. The present work investigates these issues via a thermal activation model which assumes the number of available irreversible structural transformations scales exponentially with an internal heterogeneous length scale. It is found that a distinct low temperature deformation regime exists which is dominated by the statistics of kinetic freezing, giving an approximately linear increase in yield stress as a function of decreasing temperature. This result is discussed in terms of the onset of heterogenous plasticity and eventual macroscopic material failure.