DENDRITIC GROWTH IN UNDERCOOLED MELT WITH FORCED-CONVECTION - EXPERIMENT FOR PURE SUCCINONITRILE

The flow in the melt will affect to the morphology of solidification but has rarely been studied quantitatively, because of difficulties in how to bring the controlled flow of melt to the region near the tip of dendrite. In order to realize the flow of melt, the undercooled melt in a cylindrical circular loop cell is partially heated to drive the melt and is forced to flow by the buoyancy. The dendritic growth in this forced melt flow is studied for dendrites growing horizontally in the undercooled melt of pure succinonitrile. The flow affects more significantly to the growth rate of dendrite in lower undercooling than in higher undercooling in the melt. The growth rate of the dendrite tip increases with the increase of forced melt flow when the flow is coming to the tip. When the velocity of the forced flow becomes small, the growth rate of the tip of dendrite approaches one predicted by the theory, where the dendritic growth is studied by the diffusion of heat alone under the marginal stability assumption.