|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Frontiers in Solidification: An MPMD Symposium in Honor of Michel Rappaz
||Single-Phase Filamentary Cellular Breakdown via Laser-Induced Solute Segregation
||Austin Akey, Daniel Recht, James S. Williams, Michael J. Aziz, Tonio Buonassisi
|On-Site Speaker (Planned)
||Michael J. Aziz
Ultrafast solidification of materials offers a pathway to novel structures with unusual properties. Impurity-rich silicon processed using nanosecond-pulsed-laser melting is known to undergo cellular breakdown at sufficiently high impurity concentrations, producing nanoscale features due to solidification speeds of order 1 m/s. We apply atom probe tomography (APT) to show that the morphology of cellular breakdown in these materials is significantly more complex than previously documented. We observe a branching, filamentary structure topped by a few nm of a cell-like layer. Single crystal silicon supersaturated with at least 10% atomic Co and without other phases is found within these filaments. The unprecedented spatio-chemical accuracy of APT allows us to investigate nanosecond formation dynamics. Reported properties of these materials can now be reconsidered in light of their true composition. The rapid advances in atom probe tomography are permitting an unprecedented level of understanding of ultra-fast solidification microstructures and their formation processes.