Effect of Anisotropy of Surface Energy on the Growth Direction of Solid Phase in Constrained Growth Condition

Abstract

The growth direction of solid phase, which has a great influence on the grain selection, has been investigated. Transparent organic systems, succinonitrile-H 2 O alloy and pivalic acid-H 2 O alloy have been used for unidirectional solidification. Essential parameters of phase diagrams, distribution coefficient of H 2 O (k) and liquidus slope (m) have been determined experimentally. The relationship is analyzed between dimensionless growth velocity (V=V c , where V c is the critical growth velocity for constitutional supercooling) and dimensionless growth direction ( 0 ). The change in 0 with V=V c is common and similar for both alloy systems. 0 increases rapidly at low growth velocity region. Then, 0 increases slowly and approaches unity with increasing V=V c . When the anisotropy of surface energy increases, the growth direction of solid phase becomes close to the preferred growth direction even at low growth velocity region, where cellular interface is observed.

Continued growth controlling of the non-preferred primary phase for the parallel lamellar structure in directionally solidified Ti–50Al–4Nb alloy

“…The lateral disturbance is proportional to the interface kinetic strength and the growth rate obtained through solving the diffusion equation and the directional solidified results [22,[29][30][31][32][33][34]. Then the tilting angle increases with the increase of the growth rate.…”

“…The basic understanding of the evolution of the growth direction can be obtained by examining the linear stability of a planar interface with the interface anisotropic effects [21,22,[29][30][31][32]. When the system during the directional solidification is beyond the planar interface stability threshold, the disturbance with infinitesimal amplitude will arouse the deformation of the interface.…”

Crystal orientation control in TiAl–Nb alloys through a double directional solidification process

“…During DS process, the growth direction of crystal is constrained by the combination of heat flow direction (direction of temperature gradient) and preferred growth direction, and the growth direction of primary phase is mainly controlled by preferred growth for the solid-liquid interface morphology with a dendrite type [19]. In the initial DS stage of SDS, the equiaxial dendrite segregation is developed into the directional segregation through the initial growth interface.…”