About this Abstract |
| Meeting |
2026 TMS Annual Meeting & Exhibition
|
| Symposium
|
Advances in Multi-Principal Element Alloys V: Mechanical Behavior
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| Presentation Title |
On the temperature dependence of damage tolerance in bcc refractory medium/high-entropy alloys |
| Author(s) |
Robert O. Ritchie, Andrew M. Minor, Mark Asta, Punit Kumar, David H. Cook, Xiaoyu H. Chen, Wenqing H. Wang, Madelyn H. Payne, Pedro P.P.O. Borges, Satish P.P.O. Rao |
| On-Site Speaker (Planned) |
Robert O. Ritchie |
| Abstract Scope |
Unlike fcc high-entropy alloys (HEAs) which exhibit excellent damage-tolerance from a sequence of deformation mechanisms that prolong strain hardening, bcc refractory RHEAs (despite their ultrahigh-temperature strength) are invariably prone to tensile brittleness from high ductile-to-brittle transition temperatures (DBTT). Here we examine RHEAs that contain group-IV elements, specifically a Nb45Ta25Ti15Hf15 alloy, which appears to display no DBTT, with KIc values exceeding 250 MPa√m at room temperature and 90 to 95 MPa√m at 77K to 20K. Although this alloy loses strength >1200°C, the reason for its high tensile ductility and toughness at cryogenic temperatures is quite dissimilar from that of the fcc HEAs as Nb45Ta25Ti15Hf15 has only limited strain hardening. It deforms by mechanisms of dislocation motion, twinning and TRIP (and kinking at higher temperatures), but the synergism of these processes is distinct from other bcc alloys, which we believe is the rationale for its ductile behavior at liquid-nitrogen to liquid-helium temperatures. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
High-Entropy Alloys, High-Temperature Materials, |