The long term goal of this research is to achieve a better understanding of microstructure formation during solidification. Experimental studies are conducted on mushy zone solidification to create improved models of the process. The emphasis is on mushy zone evolution, particularly in the early phases of the mushy zone formation, and how this structure couples with the large-scale transport processes associated with alloy solidification. Nucleation and grain fragmentation is observed under various flow conditions. Effects of forced convection, solute concentration, and undercooling on the fragmentation process is determined. Experiments are planned to determine how the final solid phase formation interacts with the mushy zone. %%% Success in this approach would permit development of a predictive theory for real casting and solidification processes down to the mesoscopic (0.1 - 100 micron) scale.
