|About this Abstract
||1st World Congress on High Entropy Alloys (HEA 2019)
||High Entropy Alloys 2019
||Weak-beam Dark-field STEM Study of Dislocation Microstructure in NiCoCr Medium Entropy Alloy
||Jiashi Miao, Michael Mills
|On-Site Speaker (Planned)
Equiatomic NiCoCr medium entropy alloy has exceptional mechanical properties, including high ductility, large work hardening rates and superior fracture toughness at both room temperature and cryogenic temperature. Such excellent properties are closely related to its dislocation microstructure under deformation. In this study, a newly developed defect imaging mode: weak-beam dark-field scanning transmission electron microscopy (WB DF STEM) was used to characterize dislocation dissociation, slip and cross-slip, dislocation decorrelation and interactions in this alloy. The new WB DF STEM imaging technique can offer bend-contour and thickness-fringe free dislocation images with resolution similar to those captured using conventional WB DF TEM imaging. The mechanisms of deformation twinning and deformation induced face centered cubic (FCC) to hexagonal close-packed (HCP) trasnformation in this alloy were revealed by using WB DF STEM imaging in combination with atomic-resolution STEM imaging.