Crystallization control in highly undercooled liquids and glasses

Crystallization of highly undercooled materials either from the melt during cooling or from an amorphous phase during heating can yield novel phases with useful properties, but a reliable control of phase selection has been elusive. In bulk volumes fluxing is a common method to promote high undercooling due to nucleant removal or deactivation, but the mechanism is not defined clearly. From experiments on Au with well controlled conditions the operation of fluxing has been identified as a nucleant refining process. Moreover, structural studies have discovered that fluxing can also affect the melt structure and dynamics in multicomponent alloys. During primary nanocrystallization of amorphous Al alloys, solute substitution has a significant effect on the glass forming ability and crystallization kinetics primarily through the change in diffusion that impacts the crystal nucleation rate through transient effects.