The role of gravity during solidification processing in systems exhibiting a liquid-liquid miscibility gap

Abstract Liquid miscibility gap systems are characterized by a region in which two liquids, often with very different compositions and densities, are in thermodynamic equilibrium. Upon passing through such a region during solidification processing, the density difference between the two liquids promotes rapid separation, coalescence, and, subsequently, severe macrosegregation. With the intent of minimizing this density driven segregation, the microgravity environment of space has long been envisioned as an ideal processing arena. This paper briefly considers results from previous and new studies, both Earth (unit-gravity) and microgravity based. In view of the conclusions drawn, novel methods recently developed for processing hypermonotectic alloys, on Earth, are presented and the role of the microgravity environment is reexamined.