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ISSN Online: 2377-424X

ISBN Print: 0-89116-909-1

International Heat Transfer Conference 9
August, 19-24, 1990 , Jerusalem, Israel

INFLUENCE OF MICROGRAVITY ON THE FREEZING OF AN EUTECTIC VOLUME

Get access (open in a dialog) DOI: 10.1615/IHTC9.830
pages 287-292

Abstract

This publication presents results of the GERMAN SPACE-LAB Dl MISSION, sponsored by the BMFT, FRG-Bonn.
Two specimens of an AlSi7 alloy were unidirectionally crystallized during the Dl Mission. The unidirectional crystallization was stopped by quenching the residual melt to investigate the influence of buoyancy convection on the eutectic between the dendrites.
The morphology of the eutectic structure shows a significant difference using a temperature gradient of GSF = 16K/mm crystallization rates of υSF = 5 and 8 mm/min in microgravity (μg) and gravity (lg) environments. The causes of this result are discussed.
It is stated that the buoyancy convection is responsible to the following facts: The medium phase distance λ and the medium cut face of the silicon phases are lower under microgravity. The differences decrease at higher velocities of crystallization because of microconvection in front of the solidification front. More μg experiments are projected during D2 Mission to determine the influence of lateral diffusion on the eutectic crystallization of an AISi alloy.