Effect of Thermal Drift on the Initial Transient Behavior in Directional Solidification of a Bulk Transparent Model Alloy
Résumé
In situ monitoring of directional solidification experiments on a transparent model alloy was carried out under low gravity in the Directional Solidification Insert of the Device for the Study of Critical Liquids and Crystallization (DECLIC-DSI) on-board the International Space Station. The present work is focused on the analysis of the interface recoil and its macroscopic shape evolution. Theoretically the interface movement is due to the formation of a solute boundary layer in front of the interface. However, the bulk configuration and the thermal specificities of transparent systems induce thermal effects, which are usually not observed in the classical thin sample configuration. Numerical thermal modeling highlights two thermal contributions to the interface recoil, both increasing with pulling rate. The Warren and Langer model is modified to take into account these contributions that modify the interface dynamics, and a good agreement is obtained between the experiments and the modified model.