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M: Metallphysik
M 18: Symposium: Phasenumwandlungen in Schmelzen VII
M 18.5: Talk
Tuesday, March 25, 2003, 15:45–16:00, IFW A
Phase formation in undercooled Nd-Fe-B melts under reduced gravity during parabolic flights — •Sven Reutzel1,2, Thomas Volkmann2, Jörn Strohmenger2, Jianrong Gao2,3, Heinrich Bach1, Dieter M. Herlach2, and Takeshi Okutani4 — 1Institute of Experimental Physics, Ruhr-University of Bochum, Germany — 2Institute of Space Simulation, German Aerospace Center (DLR), Köln, Germany — 3Department of Applied Physics, Nortwestern Polytechnical University, Xian, P.R. China — 4Institute for Materials and Chemical Processes, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
Crystallization behavior of undercooled Nd-Fe-B melts is investigated by electromagnetic levitation under conditions of reduced gravity during parabolic flights with respect to the phase formation of γ-Fe and the intermetallic compound Nd2Fe14B1. The aim of the experiments is to elucidate the influence of fluid flow in the melt on crystallization kinetics of the different solid phases and hence the evolution of the microstructure. Electromagnetic processing on ground causes high convection speeds of the order of 1 m/s that are significantly reduced under microgravity conditions. During parabolic flight experiments the sample is processed and solidified containerlessly using the TEMPUS facility (Tiegelfreies elektromagnetisches Prozessieren unter Schwerelosigkeit) leading to a reduced melt convection level in the sample. During the entire experiment cycle, i.e. heating, melting, cooling and solidification the temperature of the sample is recorded by a pyrometer. In addition, after the flight experiment the structural and the magnetic properties of the retrieved samples are analyzed. The results are compared to reference experiments that are performed in ground laboratory using a similar electromagnetic levitation facility.