About this Abstract |
Meeting |
2022 TMS Annual Meeting & Exhibition
|
Symposium
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Mechanical Behavior at the Nanoscale VI
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Presentation Title |
Direct Observation of Intermittent Dislocation Motions and Deformation Mechanisms in Nanocrystalline Molybdenum |
Author(s) |
Haw-Wen Hsiao, Jia-Hong Huang, Jian Min J. Zuo |
On-Site Speaker (Planned) |
Haw-Wen Hsiao |
Abstract Scope |
We report on a direct observation of intermittent dislocation activities in nanocrystalline molybdenum (Mo) in fabricated nanopillars under compression. Mo is selected as a representative refractory metal with the body-centered-cubic (BCC) structure. The size dependent plastic behaviors of BCC Mo differ significantly from these of face-centered-cubic (FCC) metals. Various mechanisms have been proposed to explain the differences, but they remain largely unverified experimentally. Here, using results obtained from in-situ electron imaging, we show that multiple mechanisms operate during the compression of nanocrystalline Mo nanopillars, starting initially from grain boundary deformation and followed by dislocation hardening before yielding. After yielding, intermittent dislocation avalanches and grain boundary dislocation transmission are observed, with dislocation intermittency dominating the plastic deformation. Dislocations of both screw and edge characters are also observed in the BCC crystal. Together, our findings here provide critical insights into the strengthening via grain refinement for a refractory metal. |
Proceedings Inclusion? |
Planned: |
Keywords |
Characterization, Mechanical Properties, Nanotechnology |