MORPHOLOGY TRANSITIONS DURING NONEQUILIBRIUM GROWTH .2. MORPHOLOGY DIAGRAM AND CHARACTERIZATION OF THE TRANSITION

In a preceding paper we have presented a new diffusion-transition approach to study pattern formation in systems described by a conserved order parameter on a square lattice. Here we describe and analyze two of the different morphologies observed during growth far from equilibrium: the dense branching morphology (DBM) and the dendritic morphology. Both have been found to represent clearly distinct morphological "phases". They can be characterized by their envelope: convex for DBM and concave for dendritic morphology. They both propagate at constant velocity. The velocity scales with different powers of the chemical potential for the two different morphologies. For the DBM, the branch width is proportional to the diffusion length. The transitions between the morphologies and their growth behavior are studied as a function of the chemical potential and the macroscopic driving force (supersaturation).