Most theoretical work on solidification focuses on dilute binary alloys, while those
commonly used in industry are multi-component with high solute concentrations. In
concentrated alloys, the diffusion of one component will be inevitably influenced by the
others, which will further affect the rapid solidification kinetics. Assuming local
non-equilibrium at the solid/liquid (S/L) interface and in the bulk liquid, the kinetics
of planar interface migration and dendrite growth in strongly non-equilibrium
solidification of Ni-Cu-Co alloys is comparatively studied. It is found that, for planar
interface kinetics, the thermodynamic interactions lead to a non-monotonic tendency of the
partition coefficient of Co with a slightly lowered interface temperature. Meanwhile, for
dendrite growth (i.e. curved interface), the curvature effect and the thermodynamic
interactions together result in the non-monotonic variation of partition coefficients. Due
to the lowered dendrite tip temperature as a result of the thermodynamic interactions,
larger undercooling is needed for interface migration and the dendrite growth is slowed
down.