Evolution of the temperature, microstructures and microsegregation in equiaxed solidification of Al-5 wt.% Cu alloy

Abstract In this study, the evolutions of the microstructures and microsegregation are related to the cooling curve in equiaxed dendritic solidification of the Al-5 wt.% Cu alloy. In addition to regular branching of dendritic arms, leaf venation branching, free branching and radial branching were also observed. With the extension of the dendritic zone, both the composition of the extra-dendritic melt and average composition of the dendritic zone change. The microsegregation mechanism in the dendritic zone deviates from the modified Scheil model. The microsegregation data suggest that the single dendritic arm is a porous structure containing the trapped boundary layer. As the temperature decreased after the isothermal periods, some original dendritic arms and interdendritic melt converged to form a new dendritic arm.