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

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.