|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Applications of Solidification Fundamentals
||Influence of Crystal Orientation on the Dynamical Selection of Propagative Cellular Solidification Patterns
||Younggil Song, Sabine Bottin-Rousseau, Silvere Akamatsu, Alain Karma
|On-Site Speaker (Planned)
We investigate the dynamics of tilted-cell patterns in dilute alloys during directional solidification of single crystals with a finite misorientation. In situ experiments and phase-field simulations in thin samples bring evidence of a selection of the cell spacing by a propagative source-sink mechanism. It operates on larger space and time scales than the competitive growth mechanism at play during the initial transient. Tertiary branching at the diverging edge of the sample (source) selects a spacing close to the upper pattern-stability limit. This spacing invades the sample to yield a uniform microstructure, except in a small region near the converging edge of the sample (sink). We propose an evolution equation for that dynamics in terms of the local dependence of the cellular drift velocity on the spacing and a generic phase-diffusion uniformization process. This fundamental knowledge is key to improving elaboration processes of single crystals or textured polycrystals for advanced materials.
||Planned: Supplemental Proceedings volume