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MM: Fachverband Metall- und Materialphysik

MM 40: Liquid and Amorphous Metals

MM 40.2: Vortrag

Donnerstag, 4. April 2019, 15:15–15:30, H46

The relaxation dynamics of a severely deformed metallic glass studied by X-ray photon correlation spectroscopy — •Hongbo Zhou¹, Sven Hilke¹, Eloi Pineda², and Gerhard Wilde¹ — ¹Institute of Materials Physics, University of Münster, 10 Wilhelm-Klemm Strasse, Münster 48149, Germany — ²Department of Physics, Universitat Politecnica de Catalunya BarcelonaTech, Esteve Terradas 8, Castelldefels 08860, Spain

The structural relaxation behavior of a metallic glass severely deformed by High- Pressure Torsion was investigated at the atomic length scale by high-resolution X-ray photon correlation spectroscopy. We find that the dynamics of the deformed sample is much faster compared with the undeformed sample, indicating that rejuvenation has occurred. Meanwhile, the structural relaxation rates and behaviors of both samples are distinct at different temperatures. It is notable that an intermittent and heterogeneous relaxation process happens at the temperature of 423 K. The activation energies of the structural relaxation below 473 K are 21.2 kJ/mol and 25 kJ/mol respectively, which demonstrates that the relaxation processes at low temperatures are stress-dominated. However, when the temperature is increased above 473 K, a crossover behavior of the effective relaxation time occurs, which is probably due to a change of relaxation mechanisms from a stress-dominated to a diffusion-dominated process.