Growth direction of cellular and dendritic interface in a constrained growth condition

Abstract

In-situ observation of unidirectional solidification using transparent substance has been performed to investigate the growth direction of solid phase. Cell and/or dendrite, the preferred growth directions of which are not parallel to the heat flow direction, were observed with various solidification conditions. Dimensionless growth direction (π′ = (angle between heat flow direction and growth direction)/(angle between heat flow direction and preferred growth direction)) changes from zero to unity with increasing growth velocity at a constant temperature gradient. Introducing the normalized growth velocity (V / Vc, where Vc is the critical growth velocity for breaking down a planar interface), the relation between π′ and growth condition could be correlated and π′ could be expressed by a unique line with respect to the normalized growth velocity. Furthermore, the growth directions of cells or dendrites under the condition of unidirectional solidification have been analyzed by the phase-field model. The calculated results agree with the experimental results and the functional relationship between growth velocity and growth direction is qualitatively explained.