  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.
