Dendritic growth

Dendritic and related cellular mi c ro structures are most commonly observed during alloy solidification, One of the key features of these growth morphologies is the tip characteristic that strongly influences the selection of solidification microstructures. Dendritic growth occurs during the solidification of undercooled melts and during the directional solidification of alloys. Both cases are examined in this paper. Analytical models of dendritic growth are discussed and applied to large deviations from equilibrium, to multicomponent alloy systems and to solid state transformations. The effect of convection on growth is also briefly presented. Furthermore, the importance of the dendrite tip temperature (i.e. the interface response for varying interface morphologies, velocities, temperature gradients, and compositions) in computing microstructure and phase selection maps is emphasized. Examples of application of such maps for solving some important solidification problems, such as hot cracking in welding of stainless steels and microstructure control for epitaxial single crystal laser deposition on SX turbine blades, are presented.