About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
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Symposium
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Mechanical Response of Materials Investigated through Novel In-situ Experiments and Modeling
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Presentation Title |
Low Temperature Failure Mechanism of [001] Niobium Micropillars under Uniaxial Tension |
Author(s) |
Seok-Woo Lee, Gyuho Song, Nicole Aragon, Ill Ryu |
On-Site Speaker (Planned) |
Seok-Woo Lee |
Abstract Scope |
Micromechanical studies have shown that the plasticity of metals at the micrometer scale is size-dependent and is controlled by the intermittent operation of dislocation sources, which leads to new phenomena such as size-affected strength and jerky plastic flow. However, the effects of low temperature on source-controlled plasticity and its related failure mechanism have not been clearly understood, yet. In this work, our in-situ cryogenic micro-tensile tests, transmission electron microscopy, and dislocation dynamic simulations on bcc niobium micropillars reveal that the suppression of cross-slip at low temperature prevents dislocation multiplication, leading to dislocation starvation. Then, dislocation nucleation occurs until stress concentration at a slip step nucleates a crack, the propagation of which leads to catastrophic brittle failure. Thus, the competition between dislocation nucleation and crack nucleation controls a failure process. Our results provide an insight in understanding of a failure process of metal micropillars at low temperature under uniaxial tension. |
Proceedings Inclusion? |
Planned: |
Keywords |
Mechanical Properties, Modeling and Simulation, Characterization |