Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 36: Amorphous and Liquid Materials IV
MM 36.1: Vortrag
Donnerstag, 30. März 2006, 16:30–16:45, IFW B
Heterogeneous dynamics in MD simulated constant-shear-rate deformations of amorphous Ni50Zr50 — •Kevin Brinkmann and Helmar Teichler — Institut für Materialphysik d. Univ. Göttingen, 37077 Göttingen
Molecular-dynamics simulations of viscoplastic deformation of amorphous Ni50Zr50 show — in agreement with experiments — a characteristic stress-strain curve with an elastic linear regime for small strains, a pronounced stress overshoot and a drop to a constant flow stress, the latter indicating the transition into the steady-state flow regime. From analyzing changes in the local topological short range order, it is found that at T=700 K strains below the upper yield point induce moderate, spatially homogenous atomic rearrangements only. Most of them are reversible, accounting for (an)elastic contributions. The marked decrease in stress between upper and lower yield point is due to a growing number of local rearrangement centers in the Zr-matrix. These rearrangements appear spatially heterogenous in the simulation cell, gradually filling a plane of maximum shear stress and forming a (micro-)shear-band. The interior of the shear-band exhibit significantly altered properties compared to topologically unchanged regions indicating a structural change in the shear-band resembling rejuvenation. At T=1000 K (Tg=1050 K), stress localization, is depressed leading to a highly unorganized formation of the structurally altered regions, rapidly covering the whole sample.