Berlin 2015 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 8: Liquid and Amorphous Metals II: Structure Formation in Metallic Glasses
MM 8.3: Vortrag
Montag, 16. März 2015, 12:15–12:30, H 0107
Effect of minor additions on the structure and dynamics of binary Zr-Cu melts — •Zach Evenson, Fan Yang, Dirk Holland-Moritz, and Andreas Meyer — Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51147 Köln
The formation of bulk metallic glasses can be greatly enhanced through the minor addition of another element, although the underlying physical mechanisms remain largely unknown and often speculative. It has been suggested that minor additions can lead to a more sluggish melt kinetics as well as thermodynamically suppress competing crystal phases. However, very few studies are actually carried out in the melt to directly test these assumptions. We report on the effect of minor additions of Al and Ti on the structure, dynamics and glass-forming ability of binary Zr-Cu liquids. In order to accurately investigate the physical properties of chemically reactive metallic melts and gain access to the metastable undercooled liquid, we employed electrostatic levitation (ESL) as a versatile containerless processing technique. Investigations of a Zr50Cu50 liquid with minor additions of only 4 at.% Al or Ti reveal a complex interplay between structure and dynamics as a result of chemical short-range order, extending beyond simple considerations based on free volume or atomic packing. The impact of minor additions on the glass-forming ability of this system is discussed in terms of non-ideal interactions between the melt constituents.