Regensburg 2007 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 9: Liquid and amorphous materials III
MM 9.1: Vortrag
Montag, 26. März 2007, 14:45–15:00, H4
Liquid phase demixing and growth in Cu-based alloys — •Matthias Kolbe1, Jianrong Gao2, Jiuzhou Zhao3, Lorenz Ratke1, and Dieter Herlach1 — 1DLR, Institut für Materialphysik im Weltraum, Linder Höhe, 51170 Köln — 2Key Lab of Electromagnetic Processing of Materials, North Eastern University, Shenyang 110004, China — 3Institute of Metal Research, CAS, Shenyang 110016, China
Cu-based alloys as Cu-Cr, Cu-Co, Cu-Nb and Cu-Fe exhibit a flat liquidus in the binary phase diagram. This property is often associated to metastable phase separation in the region of the undercooled melt: When the metastable miscibility gap is entered, the homogeneous alloy separates into a Cu-rich and a Cu-poor liquid. The undercooled melt solidifies rapidly and the metastable liquids are frozen in. Microstructure analysis of the solidified material allows the determination of properties of the metastable liquids. We studied phase separation and phase growth of the metastable Co-rich L1 phase in Co-84at%Cu by electromagnetic levitation (EML) and drop tube experiments. In addition, samples have been processed and solidified in the TEMPUS facility during parabolic flights under low gravity conditions. Compared to processing in EML on ground, the fluid flow is reduced in TEMPUS by an order of magnitude. The solidified microstructures show the influence of cooling rate and of the different convection levels in the liquid on phase growth. The results are discussed within current models of liquid phase growth.