|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Frontiers in Solidification Science and Engineering
||Impurities at Work: Integrated Imaging of Eutectic Modification
||Saman Moniri, Xianghui Xiao, Ashwin J. Shahani
|On-Site Speaker (Planned)
How do impurities impact the growth, morphology, and crystallinity of eutectic alloys? Several models have been proposed since the 1960s and onwards to explain the mechanisms leading to refinement and twinning in the impurity-modified alloys, most of which lack experimental verification. Here, we have examined the solidification pathways of an Al-51.6wt%Ge eutectic with and without trace metal impurities (0.1 wt.% Na). By monitoring the solidification process in-situ via synchrotron-based, 4D (3D space- and time-resolved) X-ray tomography (4D-XRT), we found that the Ge lamellae in the modified alloy develop curved solid-solid interfaces as growth proceeds, anomalous for a faceted phase. We attribute this curvature to the greater intra-lamellar misorientation of the Ge phase in the modified eutectic, as determined from electron backscatter diffraction analysis of the fully-solidified specimen. Further analysis of our integrated dynamic and crystallographic characterizations aims at extending Hellawell’s impurity-induced twinning model of irregular eutectic solidification.
||Planned: Supplemental Proceedings volume