Regensburg 2019 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 40: Liquid and Amorphous Metals
MM 40.5: Talk
Thursday, April 4, 2019, 16:00–16:15, H46
Decelerated Ageing in Binary Metallic Glasses by Cryogenic Thermal Cycling — •Marian Bruns and Fathollah Varnik — Ruhr Universität Bochum, Universitätsstraße 150, 44801 Bochum, Germany
Cryogenic thermal cycling is a thermal treatment where samples are exposed to an oscillatory temperature change at low temperatures. For its application to metallic glasses, cycling temperatures sufficiently below the glass transition temperature TG are employed to avoid thermally activated relaxation or annealing. It has been proposed that cryogenic thermal cycling leads to rejuvenation of aged glasses, thus improving their plasticity.
Here, we investigate this issue via molecular dynamics simulations. In contrast to previous studies, addressing static properties, we focus on dynamic aspects. We qualitatively indicate ageing, rejuvenation and their extend by comparing the mean squared displacement of as-aged and as-cycled systems. The treatment has been performed at both constant volume and constant pressure with different frequencies, depending on the time the system aged prior to the cycling. We find that the glassy system as we prepared it is not being rejuvenated by the treatment but further ageing during the cycling is observable. Nonetheless the treatment has an impact on the ageing process by slowing it remarkably down. This indicates that processes that cause ageing (i.e. structural relaxation) are in a competitive relation with processes related to rejuvenation due to thermal treatment.