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MM: Fachverband Metall- und Materialphysik
MM 56: Liquid and Amorphous Metals IV
MM 56.3: Talk
Thursday, April 3, 2014, 12:00–12:15, IFW A
Indication for a liquid-liquid phase transition during ultrafast heating of metallic glasses — •Stefan Küchemann1, Norbert Mattern2, and Konrad Samwer1 — 11. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany — 2Leibniz Institut für Festkörper- und Werkstoffprüfung Dresden, 01171 Dresden, Germany
Although the origin of the dramatic change of the dynamics in the supercooled liquid region of metallic glasses has been studied since many years, there is still no conclusive explanation for this behavior. The incipient crystallization process limits the number of possible techniques which can be used to study the supercooled liquid region of metallic glasses. In this contribution, we used an ultrafast capacitor discharge in order to heat up metallic glasses homogeneously above the glass transition temperature with typical heating rates of the order of 106 K/s [1]. For our measurements, we used melt-spun ribbons of nominal composition of Zr65Cu27.5Al7.5. At high temperatures, we studied the specific heat as well as structural changes during the crystallization at different temperatures. Therefore, X-ray measurements have been performed at P07 beamline of PETRA III at DESY. A newly developed chopper system has been used in order to enhance the temporal resolution of the 2D detector from 15 Hz up to 195 Hz. The observations will be discussed in the framework of a liquid-liquid phase transition. Financial support by DFG within SFB 602 is gratefully acknowledged.
[1] William L. Johnson et al., Science 332, 828 (2011)