Development of irregular interface morphology during unidirectional solidification of succinonitrile

This paper reports an experimental investigation on irregular interface morphology patterns developed in thin-film unidirectional solidification of pure succinonitrile. Solidification experiments have been conducted under various temperature gradients and interface velocities. Several irregular patterns have been observed including titled dendrites, degenerate dendrites, and seaweed. It is found that as the temperature gradient increases, steady titled dendrites may evolve into degenerate dendrites and eventually to seaweed. With the same grain orientation, the irregular patterns may transform from one form to another as the growth condition changes. Observations demonstrate that normal dendrites exhibit a higher growth rate than seaweed pattern and would overgrow them. Irregular pattern may also become strongly dynamic and different patterns may evolve into each other during growth within the same experiment. These results should shed a light into the understanding of the interface morphology development during solidification.