Liquid structure dependence of rapid crystallization dynamics for rare-earth terbium

Abstract

Unveiling the phase transformation mechanism for liquid rare-earth metals has been a great challenge, especially at the metastable undercooled state. Here, the liquid structure dependence of the crystallization mechanism of rare-earth terbium was investigated by electrostatic levitation experiments and molecular dynamics simulations. After achieving a maximum liquid undercooling of 206 K (0.13Tm), the thermophysical prosperities including liquid density, surface tension, viscosity, and self-diffusion coefficient were determined over a wide temperature range. The strong chemical affinity created active substrates, introducing a scenario of heterogeneous nucleation associated with interfacial energy reduction. Furthermore, dendrite growth velocity exhibited a power law relation vs undercooling, consistent with the dendritic model accounting for nonequilibrium atomic attachment. Upon cooling, the thermal evolution and electronic distribution were intrinsically coupled with the enhancement of local topological order, characterized by fivefold symmetric and crystalline configurations. These findings clarified the correlation between liquid property and atomic arrangements, providing insights relevant to advanced functional materials.