Interface morphology transitions during directional solidification in a transparent model alloy

Directional solidification experiments have been carried out on the studies of transitions either from planar to cellular interface or from cellular to dendritic one in a transparent model alloy, succinonitrile-1.1% ethanol, with the emphasis on the time-dependent development of interface morphology. The results show that paying no enough attention to the time-dependent development of interface morphology will lead to evident overestimate of the solidification velocities at which the transitions of the planar-cellular and cellular-dendritic occur. A method of finding the critical condition of interface instability by the asymptotic line of V_vs t_c curve is given from the experimental results. The effect of temperature gradient on the cellular-dendritic transition rate has been determined.