Solidification of highly undercooled Si and Si–Ge melts

✍ Scribed by C. Panofen; D.M. Herlach

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 593 KB
• Volume: 449-451
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2006.02.443

✦ Synopsis

We report growth velocity measurements of highly undercooled pure Si and Si-Ge melts (2.5 and 10.0 at.% Ge) processed by containerless electromagnetic levitation. The existence of two regimes of growth for pure Si can be confirmed: faceted growth at low undercoolings and dendritic growth at high undercoolings, separated by a transitional regime. The growth velocity-undercooling relation of pure Si can be reproduced using the Lipton-kurz-Trivedi-Boettinges-coriell-Trivedi dendrite growth model whereas the Si-Ge results show a break in the velocity-undercooling relation. The microstructure of the solidified Si-Ge samples changes from coarse elongated grains at low undercoolings to a fine grained structure at high undercoolings, which can be attributed to the change from faceted to dendritic growth.