Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Glasses II (joint session DY/DF/CPP)

CPP 17.10: Vortrag

Dienstag, 12. März 2013, 12:00–12:15, H46

From beta-relaxation to alpha-decay: Atomistic picture from molecular dynamics simulations for glass-forming Ni0.5Zr0.5 melt — •Helmar Teichler — Inst. Materialphysik, Univ Göttingen

In glass-forming melts the decay of structural fluctuation shows the well known transition from beta-relaxation (von-Schweidler law with exponent b) to alpha-decay (KWW law with exponent beta). Here we present results from molecular dynamics simulations for a metallic glass forming Ni0.5Zr0.5 model aimed at giving an understanding of this transition on the atomistic scale. At the considered temperature below mode coupling Tc, the dynamics of the system can be interpreted by residence of the particles in their neighbour cages and escape from the cages as rare processes. Our analysis yields that the fraction of residing particles is characterized by a hierarchical law in time, with von-Schweidler b explicitly related to the exponent of this law. In the alpha-decay regime the stretching exponent reflects, in addition, floating of the cages due to strain effects of escaped particles. Accordingly, the change from beta-relaxation to alpha-decay indicates the transition from low to large fraction of escaped particles.