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MM: Fachverband Metall- und Materialphysik
MM 4: Microstructure and Phase Transformations - Characterization
MM 4.4: Vortrag
Montag, 16. März 2020, 11:00–11:15, IFW B
In situ X-radiography observations of thin binary metallic alloys to investigate pattern formation and growth characteristics — •Maike Becker1, Jonathan A. Dantzig2, Laszlo Sturz3, Matthias Kolbe1, and Florian Kargl1 — 1Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft-und Raumfahrt, 51170 Köln, Germany — 2Department of Mechanical Science and Engineering, University of Illinois, Urbana, IL, 61801, USA — 3Access e.V., Intzestr. 5, 52072 Aachen, Germany
X-radiography enables the observation of the solidification process in a few hundred microns thin samples of metallic alloys in real-time. The choice of thin samples avoids a superposition of the solidification structures and exploits the X-ray contrast through a clear distinction between the solid and liquid phases. Therefore, solidification characteristics like microstructure morphologies, growth velocities or concentration changes can be determined quantitatively. These data are used to better understand the influence of important material properties on microstructure formation. For example, the anisotropy of the solid-liquid interfacial energy plays an important role in the selection of growth directions and in the selection constant of the dendrite tip (and thus influences tip radius and growth velocities). The diffusion coefficient influences the formation of higher-order dendrite arms and the interaction distance between the crystals. In this context, the experimental data is used for comparison and validation of micro- and mesoscale simulations, like phase-field and dendrite needle network models.