This program is a fundamental study of the microstructure derived from rapid solidification processing of metals. The velocity of motion of the planar interface that separates the liquid and solid is measured. Laser pulsing is employed to create a one dimensional melting pattern on thin films deposited on insulating substrates. Interface motion, undercooling, and solute trapping are determined. The experimental data should provide a quantitative test of theories for the interface velocity/undercooling function. %%% This research examines non-equilibrium conditions created by rapid solidification processing techniques, such as laser melting, ion implantation, and plasma spraying. The goal is to develop improved predictive capabilities for the material microstructure and chemical segregation that results from the processing.