About this Abstract |
Meeting |
2024 TMS Annual Meeting & Exhibition
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Symposium
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Mechanical Behavior at the Nanoscale VII
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Presentation Title |
Tension-compression Asymmetric Behavior of Screw Dislocation in Body-centered-cubic Metal Nanopillars |
Author(s) |
Alexander Horvath, Zhongyuan Li, Gyuho Song, Seok-Woo Lee |
On-Site Speaker (Planned) |
Alexander Horvath |
Abstract Scope |
Nanopillar compression studies have revealed a screw dislocation can be multiplied in body-centered-cubic (bcc) metal nanopillars via a mechanism known as surface-controlled dislocation multiplication (SCDM). In this study, we investigated SCDM in bcc niobium and molybdenum nanopillars at different stresses, temperatures, and loading directions by using atomistic simulations. Unlike all previous related computational and experimental works done only for compression, SCDM does not occur at all under tension. Instead, atomic-scale cross-slip forms jogs and vacancies. Particularly at the high tensile stress regime, either deformation twinning or dislocation nucleation occurs at a slip step that a screw dislocation creates. This strong tension-compression asymmetry will be discussed in terms of the core structure of a screw dislocation in the bcc crystal structure. Finally, for both compression and tension, mechanism maps were constructed in a temperature-stress space and are greatly useful in identifying screw dislocation behavior at the nanoscale. |
Proceedings Inclusion? |
Planned: |
Keywords |
Mechanical Properties, Modeling and Simulation, Nanotechnology |