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Undercooling and solidification of Ni2B under different conditions of convection

Binder, Sven and Herlach, Dieter (2011) Undercooling and solidification of Ni2B under different conditions of convection. 4th Int. Symposium on Physical Sciences in Space, 11. - 15. Juli 2011, Bad Godesberg, Deutschland.

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Abstract

We investigate the kinetics of crystal growth by measurements of the dendrite growth velocity as a function of undercooling during non-equilibrium solidification. Measurements are conducted under different convective flow conditions. The liquid samples are levitated and undercooled in strong alternating electromagnetic fields leading to forced convection. Inductive stirring is avoided by applying electrostatic levitation and by processing the samples in a liquid or glassy slag where only natural convection is present. Forced convection and natural convection can be reduced by performing undercooling experiments in reduced gravity. The experimental results are compared to each other in order to investigate the influence of convective flow on the growth dynamics of dendrites and the microstructure evolution in undercooled melts. The congruently melting compound Ni2B is chosen as sample system. It forms a chemically ordered intermetallic phase with growth velocities that are comparable to the fluid flow velocities in electromagnetically levitated melts. The results are analyzed within dendrite growth models and reveal that the growth velocity is essentially influenced by forced convection in strong electromagnetic.

Document Type:Conference or Workshop Item (Speech)
Title:Undercooling and solidification of Ni2B under different conditions of convection
Authors:
AuthorsInstitution or Email of Authors
Binder, Svensven.binder@dlr.de
Herlach, Dieterdieter.herlach@dlr.de
Date:13 July 2011
Keywords:Undercoling of Materials
Event Title:4th Int. Symposium on Physical Sciences in Space
Event Location:Bad Godesberg, Deutschland
Event Type:international Conference
Event Dates:11. - 15. Juli 2011
Organizer:Institut für Materialphysik im Weltraum, DLR Köln, und ESA
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):R - Vorhaben Materialforschung unter Mikro-g
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space
Deposited By: Dieter Herlach
Deposited On:28 Jul 2011 15:07
Last Modified:28 Jul 2011 15:07

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