Microsegregation in AlCu4 and the importance of accurate liquid diffusion data

Abstract

Microsegregation in an Al-4 wt % Cu alloy was investigated experimentally and theoretically to disclose the importance of accurate liquid diffusion data in models predicting microstructures. Experimentally, directional solidification with a cooling rate of 1 K/s was employed. Theoretically a two-dimensional pseudo-front tracking (PFT) model was used. The experimentally determined distribution of the main microstructural features including its Cu concentration have been compared to microstructure and concentration predictions of a 2D PFT model. The liquid diffusion coefficient used in the model was varied around recently measured values in order to check its impact on the microstructure prediction. The results clearly indicate that accurate liquid diffusion data are necessary for predictions comparing well with experiments.