Dresden 2003 – wissenschaftliches Programm
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M: Metallphysik
M 41: Postersitzung
M 41.36: Poster
Donnerstag, 27. März 2003, 14:30–16:30, HSZ
Tip splitting of Xenon Dendrites — •Oliver Wittwer and Jörg Bilgram — Laboratorium für Festkörperphysik, ETH, CH 8093 Zürich, Switzerland
We study pattern formation far from equilibrium during freezing of xenon. After disturbing the temperature distribution around a stationary growing dendrite, tip splitting can be observed. This tip splitting does not lead to the formation of sidebranches but to new morphologies e.g. seaweed, doublons and triplons [1]. We observed simultaneous growth of dendrites and seaweed which indicates that dendrites and seaweed patterns can coexist. We have determined tip velocities of dendrites and doublons. Doublons are found to grow faster than dendrites. This seems to be in agreement with results deduced numerically by Brener et al. [2],[3]. In Fourier transforms of the tip velocity of stationary growing dendrites, no characteristic frequencies could be detected indicating any tip oscillation. For dendritic growth we have found that the projection area of a dendrite increases with t2 .
[1] I. Stalder and J. H. Bilgram, Europhys. Lett. 56, 829 (2001)
[2] E. Brener et al., Europhys. Lett. 17, 535 (1992)
[3] E. Brener et al., Phys. Rev. E 54, 2714 (1996)