|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Frontiers in Solidification Science and Engineering
||In Situ Observations and Phase-field Modeling of Three-dimensional Grain-boundary Instability and Solitary Cell Dynamics during Directional Solidification of Binary Alloys
||Younggil Song, Fatima Lisboa Mota, Jorge Pereda, Jean-Marc Debierre, Nathalie Bergeon, Rohit Trivedi, Bernard Billia, Alain Karma
|On-Site Speaker (Planned)
We report unique in situ observations of grain boundary dynamics during directional solidification of a dilute succinonitrile-0.24wt%camphor alloy in the DECLIC/DSI experimental set-up aboard the International Space Station. The observations reveal the existence of a three-dimensional morphological instability of the boundary between cellular/dendritic grains with a misorientation less than 10 degrees with respect to the temperature gradient. This instability is characterized by the penetration of a local group of cells of a misoriented grain inside a nearby grain at a convergent grain boundary. Remarkably, while the invasion process starts with the penetration of a group of cells, the leader cell can detach itself from its group and grow continuously as a solitary cell inside the nearby grain. This detachment gives rise to a spatially localized crystalline defect structure. Phase-field simulations reproduce those observations and shed light on the role of grain boundary bi-crystallography in grain-boundary instability and solitary cell growth.
||Planned: Supplemental Proceedings volume