Dynamic Localization Effect of Dendritic and Eutectic Growth Patterns Stimulated by Space Fluid Flow.

Abstract

Conventional solidification theory asserts that eutectic phases solidify into only one specific morphology at a fixed undercooling when volume effects are negligible, while dendrites adopt rotationally parabolic tips. Here, experiments aboard China Space Station reveal that space fluid flow localization reshapes these dynamics: confined solute-thermal coupling near solid-liquid interfaces drives transitions among three eutectic growth patterns (worm-like, lamellar, faceted). Simultaneously, Marangoni convection at large undercoolings induces non-parabolic dendritic tip morphologies (dome-like, finger-like, needle-like). Spatially ordered separation of eutectic and dendritic zones is governed by localized spherically symmetric temperature and concentration fields arising from space fluid flow, whereas buoyancy-driven convection in terrestrial gravity environment disrupts this ordering, perturbing phase domain distributions. When solidified at a small undercooling, the weak convection during late stage preserves the near-perfect symmetry of dendrites under microgravity. These findings uncover novel dendritic and eutectic growth patterns under microgravity and may be applied to in-situ space manufacturing and controlled growth of crystals.