Studies of Maximum Supercooling and Stirring in Levitated Liquid Metallic Alloys

Mark Sellers

Nucleation—or the formation of some cluster in a medium undergoing a phase transition—is usually the initial step in a phase transition. However, this process is still not fully understood, as outstanding questions related to the role of structure, local order, and diffusion on nucleation remain unanswered. Systematic supercooling studies on metallic liquids performed using containerless processing techniques (electrostatic and electromagnetic levitation) will be presented and discussed within the context of several nucleation theories like the Classical Nucleation Theory (CNT), Diffuse Interface Theory (DIT), and Coupled-Flux theory. Initial results on several metallic systems (Zr-Pd, Cu-Zr, Zr-Pt, and Ti-Zr-Ni) suggest that the local order in the liquid and the structure of the nucleating phase are important factors to consider when studying nucleation. Meanwhile, studies on the International Space Station suggest that diffusion becomes an important factor to nucleation in quiescent liquids.