  The microsegregation and dendritic growth mode of Al-5wt%Cu alloy was
investigated. In the early solidification stage, the crystal growth mode of
interrupted growth and periodic boundary trapping will happen, which results in
the segregationless dendritic grains. Microsegregation only exists at the final
solidification stage with extremely tiny residual melt fraction. In the tiny
residual melt zone, the diffusion of solute from the enriched boundary layer to
the residual melt and the convergence of enriched boundaries produce the final
microsegregation.
