Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 27: Invited talk Rösner
MM 27.1: Hauptvortrag
Mittwoch, 9. März 2016, 09:30–10:00, H38
The secret of shear bands — •Harald Rösner — WWU Münster, Institut für Materialphysik, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany
Plasticity of metallic glasses is generally still puzzling since in contrast to crystalline materials no comparable deformation carriers such as dislocations, twins or grain boundaries exist. De-formation tests on metallic glasses performed well below the glass transition temperature have shown that the plastic flow is restricted to narrow regions called shear bands. The current understanding is that dilated zones of increased excess volume caused by shear localization enable shear softening. In my talk I will introduce a new method for quantitative density measurements in amorphous materials combining several quantitative electron scattering signals [1,2]. Density measurements in shear bands of different metallic glasses (Al88Y7Fe5, Pd40Ni40P20, Vitrelloy-105) show a unique propagation behavior; that is, alternating high and low density regions. Similar behavior has been reported for granular media, but not for amorphous solids. One important implication is that individual shear bands apparently propagate via local, segment-wise stick-slip that might originate from their complex topology. These results suggest connections to the physics of granular materials and jammed systems.
[1] H. Rösner, M. Peterlechner, C. Kübel, V. Schmidt, and G. Wilde, Ultramicroscopy 142 (2014) 1-9.
[2] V. Schmidt, H. Rösner, P.M. Voyles, M. Peterlechner, G. Wilde, Physical Review Letters 115 (2015) 035501.