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–H₂O alloy and pivalic acid–H₂O alloy have been used for unidirectional solidification. Essential parameters of phase diagrams, distribution coefficient of H₂O (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 (π′). The change in π′ with V⁄V_c is common and similar for both alloy systems. π′ increases rapidly at low growth velocity region. Then, π′ 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.