Regensburg 2000 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
M: Metallphysik
M 8: Struktur und Umwandlung III
M 8.8: Vortrag
Dienstag, 28. März 2000, 17:15–17:30, H16
Solidification behaviour of undercooled Si melts — •Riping P. Liu1,2 and Dieter M. Herlach1 — 1Institut für Raumsimulation, Deutsches Zentrum für Luft- und Raumfahrt (DLR) e.V., D-51170 Köln — 2Materials Science and Chemical Engineering Institute, Yanshan University, Qinhuangdao 066004, Hebei, P.R. China
Undercooling and solidification of bulk Si samples are studied both experimentally and theoretically. Bulk samples of Si as large as 7.6 mm in diameter were processed by electromagnetic levitation method. The temperature of the sample during heating and cooling processing was examined by pyrometers. An undercooling up to 330 K before solidification has been reproducibly achieved. Transition from faceted growth at a lower undercooling to continuous growth at a higher undercooling was observed through analyses of changes in phase morphologies on the surface of the samples. This transition is also examined through thermodynamic analyses on the solid/liquid interface. The free energy change of the interface as a function of undercooling and the ratio of the occupied site on the interface is presented. The results show that this transition appears before the undercooling reaches 360 K.
Support from the Alexander von Humboldt Foundation is gratefully acknowledged.