About this Abstract |
| Meeting |
2026 TMS Annual Meeting & Exhibition
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| Symposium
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Bridging Scales: Deformation and Damage Mechanisms in Microstructurally and Compositionally Complex Metallic Alloys
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| Presentation Title |
On the Toughening Deformation Mechanisms in a NbTaTiHf Refractory HEA at Cryogenic and Room Temperatures |
| Author(s) |
Xiaoyu Chen, Wenqing Wang, Velimir Radmilovic, David Cook, Madelyn Irene Payne, Satish Rao, Mark Asta, Punit Kumar, Robert Ritchie, Andrew Minor |
| On-Site Speaker (Planned) |
Xiaoyu Chen |
| Abstract Scope |
BCC refractory high entropy alloys (RHEAs) have demonstrated exceptional high-temperature strength but often suffer from brittleness at low temperatures. The Nb45Ta25Ti15Hf15 (NTTH) RHEA shows high room temperature (RT) as well as cryogenic temperature fracture toughness. In this study, we performed multi-length scale characterization of the deformation mechanisms in NTTH responsible for the exceptional damage tolerance. At RT we captured the formation and growth of kink bands at the micrometer scale using in-situ EBSD, followed by in-situ TEM experiments of these same kink bands where we observed dislocation motion associated with the kink band growth. At sub-nanometer scale, unusual edge dislocation core structures on the kink band boundary were revealed by HRSTEM imaging. For cryogenic temperature deformation, extensive stress-induced twinning and omega phase transformation at the crack tip coupled with dislocation motion inhibits a ductile-brittle transition at 20 K. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
High-Entropy Alloys, Mechanical Properties, Characterization |