| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Mechanical Behavior at the Nanoscale V
|
| Presentation Title |
Ductile-to-Brittle Transition of Micron-sized Niobium at Cryogenic Temperature |
| Author(s) |
Gyuho Song, Seok-Woo Lee |
| On-Site Speaker (Planned) |
Gyuho Song |
| Abstract Scope |
Ductile-to-brittle transition (DBT) of body-centered-cubic (bcc) metals usually occurs due to the low mobility of screw dislocation at a low temperature. The DBT behavior of micron-sized bcc metals could be different from that of their bulk counterparts because of the different plasticity mechanism, the intermittent operation of dislocation sources at the micrometer scale. In this presentation, we present our recent results on the DBT of micron-sized niobium. Micro-tensile tests were performed on [0 0 1] Nb micropillars at 298, 100 and 56K using a custom-built in-situ cryogenic micromechanical testing system. Fractography shows plasticity-driven fracture at 298K but brittle fracture at 100 and 56K. Post-mortem transmission electron microscopy suggests that the DBT at the micrometer-scale would occur via the dynamic annihilation of dislocation sources instead of the reduction of screw dislocation mobility. At a low temperature, dislocation multiplication seems to be strongly suppressed, and all dislocation sources would be quickly depleted. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |