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MEASUREMENT OF DENDRITE GROWTH ON Al-Ni ALLOYS IN REDUCED GRAVITY

Lengsdorf, Roman and Galenko, Peter and Herlach, Dieter (2009) MEASUREMENT OF DENDRITE GROWTH ON Al-Ni ALLOYS IN REDUCED GRAVITY. In: Proceedings of the 19th ESA Symposium on European Rocket and Balloon Programmes and Related Research, ESA SP-671, pp. 355-360. 19th ESA Symposium on European Rocket and Balloon Programmes and Related Research, 7.-11. Juni 2009, Bad Reichenhall. ISBN 978-92-9221-235-3.

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Abstract

It is well known that the growth kinetics in metallic melts controls microstructure evolution. If the melt is cooled below its equilibrium melting temperature prior to solidification, the state of a metastable undercooled melt is created. An undercooled melt possesses an enhanced free energy that enables the liquid to choose solidification pathways into various metastable solids of properties being different to their stable counterparts. A very efficient method to undercool a metallic liquid is the application of containerless processing a liquid drop such that heterogeneous crystal nucleation on container walls is completely avoided. Electro-magnetic levitation is a power-full technique to produce a freely suspended drop without any contact to a solid or liquid medium with the extra benefit that it is accessible for direct observation of solidification far from equilib-rium by proper diagnostic means. Under terrestrial conditions, strong electromagnetic fields are needed to compensate the gravitational force. That, in turn, causes forced convection inside the liquid drop and influences mass and heat transport, and consequently, crystal growth in undercooled melts. If the reduced gravity environment is utilized the forces to compensate residual accelerations are several orders of magnitude smaller than the levitation force on Earth. In the present paper we report on results obtained in the Earth laboratory, during parabolic flight missions and during TEXUS 44 flight in 2008 using the TEMPUS facility for containerless processing of metals in space. The results are discussed within dendrite growth theory and give evidence for strong effects of gravitational driven effects in the solidification dynamics.

Document Type:Conference or Workshop Item (Speech, Paper)
Title:MEASUREMENT OF DENDRITE GROWTH ON Al-Ni ALLOYS IN REDUCED GRAVITY
Authors:
AuthorsInstitution or Email of Authors
Lengsdorf, RomanRuhr-Universität Bochum
Galenko, Peterpeter.galenko@dlr.de
Herlach, Dieterdieter.herlach@dlr.de
Date:September 2009
Journal or Publication Title:Proceedings of the 19th ESA Symposium on European Rocket and Balloon Programmes and Related Research, ESA SP-671
Refereed publication:Yes
In ISI Web of Science:No
Page Range:pp. 355-360
ISBN:978-92-9221-235-3
Status:Published
Keywords:Undercooling, containerless processing
Event Title:19th ESA Symposium on European Rocket and Balloon Programmes and Related Research
Event Location:Bad Reichenhall
Event Type:international Conference
Event Dates:7.-11. Juni 2009
Organizer:European Space Agency
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
Deposited By: Dieter Herlach
Deposited On:02 Mar 2010 11:29
Last Modified:12 Dec 2013 20:54

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