Solidification of Atomized Liquid Droplets

The overall analysis of the microstructures developed during atomized droplet solidification requires an understanding of the nucleation and growth kinetics as well as the thermal history that operate during processing. Following the subdivision of a liquid volume into droplets, the basic nature of nucleation as a stochastic process and the activity of various catalysts play a major role in determining the droplet microstructure. Droplet thermal history including liquid undercooling and recalescence under the influence of the external cooling rate is another important component of the solidification behavior and microstructure development in alloys and the particle incorporation modes that can be observed in composite processing. The central role of kinetic control and thermal history is highlighted near a phase selection transition where the kinetic competition can result in drastic microstructure changes that are sensitive to slight variations of the processing conditions.