Solute redistribution in far from equilibrium liquid and vapor phase growth

The redistribution of solute in far from equilibrium alloy phase transformations plays a crucial role in determining the physical properties of the resulting materials. We characterize this redistribution in both liquid and vapor phase growth through a variety of experimental and theoretical methods.; First, we use a thin film laser resolidification technique on a dilute Ni(Zr) alloy to measure the relevant parameters characterizing solute trapping during rapid solidification: the diffusive speed and liquid diffusivity. In addition, the dendrite tip velocity-undercooling function is obtained in the same alloy and compared to theoretical predictions using our measured solute trapping parameters. These results successfully provide the first parameter-free test of alloy dendrite growth models.; Next, we examine the degree of congruent transfer in pulsed laser deposition of alloy thin films in phases that are stable over a wide range of compositions. We determine that the non-congruent transfer in the steady state is due to differential scattering in the plume itself. In the transient regime, non-congruent transfer is consistent with non-steady state partitioning of the target during resolidification. Additionally, we measure the local composition of particulates in the films and find that their average composition maintains the stoichiometry of the targets.; We propose a new model for surface segregation during vapor phase growth that takes into account multiple mechanisms for segregation. We include mechanisms for interlayer exchange as well as exchange at step edges. The resulting behavior of the segregation length shows temperature, velocity and orientation dependence all of which have been observed in experiments. Our analytic model is compared to experimental measurements and we find very good agreement using realistic energies.; Finally, we use a kinetic Monte Carlo simulation to model segregation during vapor deposition on FCC (111) metal surfaces with step-edge barriers. In the low segregation regime where the segregation length is on the order of the interfacial roughness, the segregation length is Arrhenius and dependent on the surface roughness. Pulsed deposition reduces the roughness and segregation length while maintaining a better uniformity of segregating atoms in each atomic layer. We propose a step-mediated climb mechanism to explain our results.