|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Mechanical Behavior of Nanostructured Materials
||L-168: Surface Rebound of Relativistic Dislocations Directly and Efficiently Initiates Deformation Twinning
||Qingjie Li, Ju Li, Zhi-Wei Shan, Evan Ma
|On-Site Speaker (Planned)
Recent experiments on small-volume metals have shown that deformation twinning (DT) initiates at ultra-high stresses and on a very short timescale. This indicates strongly correlated dislocation dynamics which remain poorly understood. Using atomistic simulations, we demonstrate that under a wide range of laboratory experimental conditions DT can be accomplished by surface rebound of relativistic dislocations. A dislocation nucleated under high stresses can accelerate to near the sound speed within a distance of 10^1 nanometers. The resulting high-speed dislocation rebounds back when hitting a free surface. The ensuing rebounds, back and forth from opposing surfaces, lead to self-sustained breeding of twinning partial dislocations, directly initiating DT. Due to its stronger temporal correlation, surface rebound sustained (SRS) relay of twinning dislocations is shown to be dominant in initiating DT over thermally activated nucleation (TAN). This dislocation breeding mechanism may also play a role in other high-stress and high-strain-rate deformation processes.
||Planned: Supplemental Proceedings volume