Microsegregation and dendritic growth mode of Al-5wt%Cu alloy based on non-equilibrium mush zone model

TL;DR

This paper investigates the microsegregation and dendritic growth modes of Al-5wt%Cu alloy during solidification, highlighting the roles of non-equilibrium mush zone processes in microstructure formation.

Contribution

It introduces a non-equilibrium mush zone model to explain microsegregation and dendritic growth behaviors in Al-Cu alloys during solidification.

Findings

Interrupted growth leads to segregationless dendrites

Microsegregation occurs only at final solidification stage

Diffusion in residual melt causes microsegregation

Abstract

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.