From the stability of cells to the mean behavior of growth fronts: A directional solidification study

An interesting issue for growth interfaces consists in linking the statisti cal features of a growth interface to the behavior of its individual cells. Focussing attention on the cell spacing, we experimentally determine the i nstability diagram for the instabilities that change the number of cells. W e then link the main features of this diagram to the evolution of the mean cell spacing with the growth velocity V. This enables us to recover the S-l ike shape of the Lambda (V) curve and the coincidence between the raising b ranch of this curve and the sudden appearance of a large density of dendrit es on the front.