|About this Abstract
||MS&T21: Materials Science & Technology
||Probing Defect Properties and Behavior under Mechanical Deformation and Extreme Conditions
||In-situ Transmission Electron Microscopy of Intermittent Dislocation Activities and Deformation Mechanisms
||Jian Min J. Zuo, Haw-Wen Hsiao, Yang Hu, Qun Yang
|On-Site Speaker (Planned)
||Jian Min J. Zuo
We report on the observation of dislocation activities in compressed nanopillars using in-situ transmission electron microscopy (TEM) and the measurement of load- and displacement-time curves. Using this technique, the dislocation and grain boundary (GB) activities can be directly correlated with the mesoscopic mechanical response for a direct determination of deformation mechanisms. The results of such study for a range of materials will be presented, including nanocrystalline materials and high entropy alloys (HEAs). In the case of HEAs, we provide evidences of dislocation slip band formation and it is relationship to dislocation avalanches. In case of nanocrystalline materials, we follow the development of dislocations and dislocation motions in the selected nanograins. The observations reveal the mechanism of dislocation hardening, grain boundary deformation, and intermittent dislocation avalanches across multiple grains. Together, these results provide critical insights about nanoscale deformation mechanisms and their critical roles that contribute to the strength and plasticity.