Regensburg 2016 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 4: Liquid and Amorphous Metals I: Glassy dynamics
MM 4.3: Vortrag
Montag, 7. März 2016, 10:45–11:00, H52
Atomic-scale structural changes during a liquid-liquid transition in a Zr-based bulk metallic glass forming alloy — •Moritz Stolpe1, Shuai Wei2, Isabell Jonas3, William Hembree1, Zach Evenson4, Fan Yang3, Andreas Meyer3, and Ralf Busch1 — 1Lehrstuhl für Metallische Werkstoffe, Universität des Saarlandes, Saarbrücken — 2Department of Chemistry and Biochemistry, Arizona State University, Tempe — 3Institut für Materialphysik im Weltraum, DLR, Köln — 4Heinz Maier-Leibniz Zentrum, TU München, Garching
Liquid-liquid phase transitions (LLTs) are considered as a possible source to explain anomalous changes in the viscous behavior, a phenomenon known as fragile-strong transition.
Using synchrotron X-ray scattering combined with electrostatic levitation we investigated the structural evolution of Zr-based metallic glass forming alloy from above the liquidus temperature down to the glass transition temperature Tg. Our study reveals a LLT from a less ordered high temperature to a more ordered low temperature phase which, thermodynamically, manifests as a smeared-out peak in the heat capacity. Although no notable density change is observed, marked structural changes in both, short- (SRO) and medium range order (MRO) occur. Our results imply that in particular the structural evolution at MRO is related to the experimentally observed change in the viscous behavior. This is in agreement with the conception that the viscous slowdown is related to an extension of MRO through an aggregation of energetically-preferred atomic clusters.