Dresden 2014 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 11: Microstructure and Phase Transformations II - Nucleation/Solidification
MM 11.6: Vortrag
Montag, 31. März 2014, 12:45–13:00, IFW B
Dendritic growth kinetics of undercooled Fe-B alloy melts — •Christian Karrasch1,2, Thomas Volkmann1, and Dieter Herlach1,2 — 1Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany — 2Institut für Experimentalphysik IV, Ruhr-Universität Bochum, 44780 Bochum, Germany
In metallic alloys dendritic growth is the major crystal growth mode controlling the evolution of the microstructure during solidification. The present work investigates the growth kinetics on pure Fe and Fe-B alloy melts in order to verify models for dendritic growth in undercooled melts. In detail, we analyze the effect of solute redistribution and solute trapping on the rapid growth of dilute Fe-1 at.% B alloy with B showing a small partitioning coefficient. For in-situ studies on deeply undercooled melts electromagnetic levitation technique (EML) is used. The rapid solidification is recorded by a high-speed camera. Undercoolings from 50 K to 300 K prior to solidification leads to growth velocities of several cm/s up to m/s. Concerning terrestrial EML the electromagnetic field necessary for levitation induces strong convective fluid flow inside the melt. To investigate the effect of convection on the growth kinetics experiments on parabolic flight are carried out under reduced gravity conditions. The microstructure of the solidified sample is analyzed by SEM and EBSD. Experimental results will be presented and discussed in the frame of current models for dendritic growth in undercooled melts. This research work is supported by DFG contract HE1601/18 and by ESA under contract 4200020277 and 4200014980.