Constrained Solidification in High Rate and Transition of Morphology

Solidification morphology in high rate is studied in the constrained solidification of organic material. Tip radius of curvature of needle crystal has decreased with growth rate by power -1/2, irrespective of interfacial shape, dendrite or cellular. Primary arm spacing of needles has decreased with growth rate, and it has diverged at some critical high growth rate. It has resulted very far from dendrites to each other. It is observed that, near the critical rate, some dendrites predominantly grow and their higher order arms develop in the interdendritic region. These arms will grow to cellular morphology above the critical growth rate.