Study of microsegregation in Al-Cu-Zn ternary alloys by experiment and Scheil model

The solidification path and microsegregation during primary solidification of Al-Cu-Zn alloy were investigated comparably by CALPHAD coupled with Scheil model, simple Scheil equation and experiment. It is indicated by the CALPHAD that the solute content at the end point of primary solidification changes synchronistically with the start point, and solute content in dendritic arm and the partition coefficient increase with the solid fraction. Simple Scheil equation is shown to be able to calculate the eutectic amount on the base of partition coefficient calculated by thermodynamics, its prediction for the different solutes is self-consistent and agreeable with the CALPHAD. The eutectic amount and SDAS were measured in DC experiment and compared to model value. It is shown that the experimental data are in agreement with the model prediction.