Thermosolutal convection during vertical Bridgman solidification of multielement compound crystals

The thermosolutal convection during directional solidification of multi-element compound crystals alloy in vertical Bridgman configuration arises from the interaction between temperature and solute gradients in the bulk melt. Both the gradients are determined by the alloy's thermophysical properties and the design of the growth configuration. The flow patterns and the solute profiles caused by the thermosolutal convection have an extremely rich structure. In this paper, taking GeSi binary alloy for example, a numerical analysis of thermosolutal convection in vertical Bridgman furnace was performed to study the effects of thermal Rayleigh Number, thermophysical properties and the design parameters of growth configuration on the thermosolutal convection and radial solute segregation. The results showed that the flow in the melt is driven by both the discontinuity of thermal boundary conditions and the difference of the thermophysical properties between melt and crystal. Meanwhile, the radial solute segregation undergoes two minima when the intensity of flow increases. So, the measures that aim at reducing the intensity of thermosolutal convection may not improve the radial solute segregation.