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J. Chim. Phys.
Volume 96, Number 6, June 1999
Page(s) 997 - 1004
DOI: 10.1051/jcp:1999186

J. Chim. Phys. Vol. 96, N°6  p. 997-1004

Convection and phase change in multi-component systems. Growth of Ga-Ge and Pb-30%Tl

A. Lamazouade, M. El Ganaoui, P. Bontoux and D. Morvan

IRPHE -Château Gombert, UMR 6594 CNRS, Université d'Aix-Marseille II, 38 Joliot-Curie, 13451 Marseille Cedex 20, France

The Bridgman technique is a directional solidification technique. The material is loaded into an ampoule, and solidified by varying the temperature field with a translation of the ampoule through a furnace. The hydrodynamic is governed by both thermal and solutal convective instabilities. The resolution of the problem uses an homogenized formulation of the conservation equations, the enthalpy approach, issued from classical mixture theory. The numerical simulation is done using a finite volume method. We present here studies on two types of Bridgman configurations. The first one, corresponding to an inverse Bridgman configuration (heated from below), shows the interaction between the interface and the hydrodynamic of the unsteady melt. The second one shows the solidification of a binary alloy in a normal Bridgman configuration, and shows the influence of thermo-solutal convection on the crystal constitution.

La technique de Bridgman est une technique de solidification dirigée. Le matériau, initialement fondu au sein de l'ampoule est solidifié durant le déplacement d'un gradient thermique. L'hydrodynamique du bain fondu est gouvernée par la compétition entre les instabilités thermiques et solutales . On utilise une formulation homogénéisée des équations de conservation dite enthalpique. L'approximation numérique utilise une méthode de volumes finis. Nous présentons ici les résultats de deux types de configurations. La première, correspondant à la configuration Bridgman inverse (chauffage par le bas), montre l'interaction entre la convection dans le bain fondu et les déformations de l'interface. La deuxième porte sur la solidification d'un alliage binaire en configuration normale et montre l'influence de la convection thermo-solutale sur la constitution du cristal.

Key words: Bridgman technique -- instabilities -- enthalpy approach -- finite volume method

© EDP Sciences 1999

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