Regensburg 2004 – wissenschaftliches Programm

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M: Metallphysik

M 12: Phasenumwandlungen II

M 12.2: Vortrag

Dienstag, 9. März 2004, 10:30–10:45, H16

In-situ Determination of Phase Selection Sequences in Undercooled Ti-Fe-Si-O Melts — •Oliver Heinen, Dirk Holland-Moritz, Thomas Volkmann, Jörn Strohmenger, Thomas Lierfeld, Sven Reutzel, and Dieter M. Herlach — DLR, Institut für Raumsimulation, D-51170 Köln

The alloy system Ti-Fe-Si-O shows a great variety of complex stable and metastable phases. Depending on the composition and the undercooling different solidification pathways are found. The large number of alloy phases in Ti-Fe-Si-O leads to a strong competition of phase selection during rapid solidification of undercooled melts. In order to determine the phase formation sequence in these alloys as function of composition and to examine possible dependencies on the short-range order of the undercooled liquid, in situ investigations of the solidification pathways and the short-range order of the liquid were performed. The containerless processing technique of electromagnetic levitation for deeply undercooled metallic melts was combined with energy dispersive diffraction of synchrotron radiation at the European Synchrotron Radiation Facility (Grenoble). This enables us to directly determine the crystal structure of the solid phases formed during rapid solidification with a time resolution of 1-2 seconds and study the short-range order of the liquid in the same experiment. Depending on the undercooling, several different solidification sequences were found. This work was financially supported by DFG under contract No. Ho1942/4 and by ESRF.