Stability of eutectic interface during directional solidification

摘要

Directional solidification of eutectic alloys shows different types of eutectic morphologies. These include lamellar, rod, oscillating and tilting modes. The growth of these morphologies occurs with a macroscopically planar interface. However, under certain conditions, the planar eutectic front becomes unstable and gives rise to a cellular or a dendritic structure. This instability leads to the cellular/dendritic structure of either a primary phase or a two-phase structure. The objective of this work is to develop a fundamental understanding of the instability of eutectic structure into cellular/dendritic structures of a single phase and of two-phases. Experimental studies have been carried out to examine the transition from a planar to two-phase cellular and dendritic structures in a ceramic system of Alumina-Zirconia (Al(sub 2)O(sub 3)-ZrO(sub 2)) and in a transparent organic system of carbon tetrabromide and hexachloroethane (CBr(sub 4)-C(sub 2)Cl(sub 6)). Several aspects of eutectic interface stability have been examined.