Dresden 2006 – wissenschaftliches Programm
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MM: Metall- und Materialphysik
MM 13: Symposium Modern Metallic Materials Design III
MM 13.9: Vortrag
Dienstag, 28. März 2006, 12:45–13:00, IFW B
Solidification of undercooled Si, Si-Co and Si-Ge melts — •Christian Panofen1, Riping Liu2, and Dieter M. Herlach1 — 1Institue of Space Simulation, German Aerospace Center (DLR), 51147 Köln, Germany — 2Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao 066004, P. R. China
Pure Si, dilute Si-Co and Si-Ge melts were undercooled and solidified containerlessly by electromagnetic and electrostatic levitation techniques in a high purity environment. Large melt undercoolings of up to 330 K were achieved by this experiment procedure.
Crystallization of the undercooled melt was externally triggered by a nucleation stimulus needle at preselected undercooling and well defined position at the surface of the sample. In this way the velocity of the solidification front was measured as a function of undercooling by using a high speed CCD camera to record the propagation of the solid-liquid interface through the undercooled melt. High growth velocities of pure Si up to 16 m/s were determined.
The growth behavior was analyzed within current theories of crystal growth in undercooled melts. Special emphasis was placed to the transition from faceted planar to dendritic growth. The results of the growth measurements were correlated to microstructure formation upon undercooling prior to solidification.
This work is funded by the Sino-German Science Center, Beijing, DFG HE-1601/16