Spiraling eutectic dendrites

TL;DR

This study uses phase-field theory to analyze the formation and patterns of eutectic dendrites in a ternary system, revealing how their shapes, including spirals, depend on physical parameters.

Contribution

It introduces a detailed phase-field model for eutectic dendrites, highlighting the stochastic selection of spiral patterns and their dependence on tip radius and anisotropy.

Findings

Eutectic and one-phase dendrites have similar shapes.

Tip radius scales with interface free energy.

Spiral patterns are stochastically selected with a distribution.

Abstract

Eutectic dendrites forming in a model ternary system have been studied using the phase-field theory. The eutectic and one-phase dendrites have similar forms, and the tip radius scales with the interface free energy as for one-phase dendrites. The steady-state eutectic patterns appearing on these two-phase dendrites include concentric rings, and single- to multiarm spirals, of which the fluctuations choose, a stochastic phenomenon characterized by a peaked probability distribution. The number of spiral arms correlates with tip radius and the kinetic anisotropy.