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Flow effects on the dendritic microstructure of AlSi-base alloys

Ratke, Lorenz and Genau, Amber and Steinbach, Sonja (2009) Flow effects on the dendritic microstructure of AlSi-base alloys. ICSSP-4, 20. Nov. - 23. Nov. 2009, Chennai, India.

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Abstract

Fluid flow changes heat and mass transport during solidification, thereby affecting the evolution of the microstructure. In order to quantify effects of convection, it is important that fluid flow can be modified experimentally. We performed directional solidification experiments with binary AlSi alloys of different compositions, using a microgravity environment for diffusive solidification and adding rotating magnetic fields to generate flow. Flow velocities up to 10 mm/s and various solidification velocities were realized while maintaining a constant temperature gradient at the solid-liquid interface. The microstructure observed in samples processed on earth and in space is characterized by primary and secondary dendrite arm spacing and the fractal dimension of the dendrites. It is found that fluid flow usually accelerates growth and coarsening of the dendritic structures and leads to new kinetic laws. The branching of dendritic networks, however, is hardly affected by flow.

Document Type:Conference or Workshop Item (Speech)
Title:Flow effects on the dendritic microstructure of AlSi-base alloys
Authors:
AuthorsInstitution or Email of Authors
Ratke, Lorenzlorenz.ratke@dlr.de
Genau, AmberUNSPECIFIED
Steinbach, SonjaUNSPECIFIED
Date:November 2009
Status:Published
Keywords:Dendritic solidification, mushy zone, fluid flow, rotating magnetic fields, fractals
Event Title:ICSSP-4
Event Location:Chennai, India
Event Type:international Conference
Event Dates:20. Nov. - 23. Nov. 2009
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: Prof. Lorenz Ratke
Deposited On:25 Nov 2009 10:22
Last Modified:12 Dec 2013 20:46

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