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Dendrite Growth Velocity in Levitated Undercooled Nickel Melts

Funke, O. and Phanikumar, G. and Galenko, P. K. and Chernova, L. and Reutzel, S. and Kolbe, M. and Herlach, D. M. (2006) Dendrite Growth Velocity in Levitated Undercooled Nickel Melts. Journal of Crystal Growth, 297 (1), pp. 211-222. Elsevier B.V.. DOI: 10.1016/j.jcrysgro.2006.08.045.

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Abstract

Model predictions for the dendrite growth velocity at low undercoolings are deviating significantly from experimental data obtained in electromagnetic levitation with a Capacitance Proximity Sensor (CPS) [K. Eckler, D.M. Herlach, Mater. Sci. Eng. A <b>178</b> (1994) 159]. In addition to that, previous data sets obtained by different techniques are not in good agreement with each other. For instance, growth velocity data for nickel melts obtained with a high-speed camera system [D.M. Matson, in: Solidification 1998, TMS, Warrendale PA, 1998, p. 233] show higher values at low undercoolings than data obtained with the CPS. Within this work new measurements of dendritic growth velocity in levitated undercooled nickel samples were performed as a function of undercooling <font face="Symbol">D</font>T to investigate this discrepancy. Solidification of the undercooled melt was detected at undercooling levels within the range of 30 K &lt; <font face="Symbol">D</font>T &lt; 300 K. The new data reveal high accuracy and low scattering. These data are compared with two independent growth velocity data sets and discrepancies are discussed. For verification of the new CPS data dendrite growth velocity was also measured by using a high-speed camera where the morphology of the intersection of the solidification front with the sample surface was investigated. The new experimental data are analyzed within the model of dendrite growth obtained on the basis of Brener's theory [E. Brener, J. Cryst. Growth <b>99</b> (1990) 165] and the model of dendrite growth with melt convection in a solidifying levitated drop, presently being developed. Special attention is paid to the effects of convection and small amounts of impurities on the growth dynamics at small undercoolings.

Document Type:Article
Title:Dendrite Growth Velocity in Levitated Undercooled Nickel Melts
Authors:
AuthorsInstitution or Email of Authors
Funke, O.UNSPECIFIED
Phanikumar, G.UNSPECIFIED
Galenko, P. K.UNSPECIFIED
Chernova, L.UNSPECIFIED
Reutzel, S.Ruhr-Universität Bochum
Kolbe, M.UNSPECIFIED
Herlach, D. M.UNSPECIFIED
Date:2006
Journal or Publication Title:Journal of Crystal Growth
Volume:297
DOI:10.1016/j.jcrysgro.2006.08.045
Page Range:pp. 211-222
Publisher:Elsevier B.V.
Status:Published
Keywords:Unterkühlung von Materialien
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W FR - Forschung unter Weltraumbedingungen (old)
DLR - Research area:Space
DLR - Program:W FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):W - Vorhaben Materialforschung unter Mikro-g (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space > Institute of Space Simulation > Center for Solidification of Undercooled Melts (ZEUS)
Deposited By: Dr.rer.nat. Sven Reutzel
Deposited On:04 Dec 2006
Last Modified:12 Dec 2013 20:21

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