2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 7: Yang Intl. Symp. / Multiscale Material Mechanics
| Editors: | Kongoli F, Aifantis E, Wang H, Zhu T |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2016 |
| Pages: | 190 pages |
| ISBN: | 978-1-987820-48-5 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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The stress-velocity relationship of dislocations and their speed limits
Yujie Wei1;1LNM, INSTITUTE OF MECHANICS, CHINESE ACADEMY OF SCIENCES, Beijing, China;
Type of Paper: Regular
Id Paper: 451
Topic: 1
Abstract:
Dislocation mobility as a function of stress is the fundamental law for the deformation in crystalline materials. However, even cutting-on-edge microscopes are incapable of recording the position of a stressed dislocation within the fine time window. Hence direct observation for one to deduce the speed-stress relationship of dislocations is still missing. Using large-scale molecular dynamics simulations, we obtain the angstrom scale spatial and picosecond level temporal information of an obstacle-free twinning partial dislocation in face centred cubic crystals. The dislocation exhibits two limiting speeds: The first is subsonic and occurs when the resolved shear stress is on the order of hundreds of megapascal. While the stress is raised to gigapascal level, an abrupt jump of dislocation velocity, from subsonic to transonic, occurs. The two-speed limits are governed respectively by the local transverse and longitudinal phonons associated with the stressed dislocation, as the two types of phonons influence dislocation gliding at different stress level.