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MM: Fachverband Metall- und Materialphysik

MM 13: Microstructure and Phase Transformations - Processing and Imaging

MM 13.1: Vortrag

Montag, 16. März 2020, 15:45–16:00, IFW B

High-gravity processing of metals at elevated temperatures — •Štefan Stanko, Mihai Stoica, Josef Hecht, Erwin Fischer, and Jörg F. Löffler — Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland

Research into ultracentrifugation is generally limited to molecular biology, biochemistry and polymer science. To investigate the behavior of metals at ultrahigh gravity, a unique centrifuge was designed and built in-house. The apparatus is capable of achieving an acceleration of more than 50,000 g together with a temperature of up to 1,200 ^∘C. At this acceleration, the sedimentation of atoms in solid solution is expected to play an important role, and the pressure gradient within the sample has an effect on the thermodynamics of the system. Under ultrahigh gravity, more phases may be observed than predicted by the Gibbs phase rule due to the effect that the chemical potentials of the various phases become gravity dependent. The processing method can also be used to explore eutectic compositions in complex multicomponent alloys. In this work, we investigate the effect of acceleration on the crystallization of pure metals such as aluminum and tin. The metals were molten and slowly cooled to room temperature at an acceleration of 26,000 g. They were then characterized via metallurgical methods as well as scanning and transmission electron microscopy. The results on the sedimentation and nanoscale microstructure obtained via this high-temperature centrifugal processing are presented and discussed.