Abstract
Post irradiation examination of two commercial tantalum alloys (based on Ta-8 %W) revealed significant irradiation hardening following neutron irradiation in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Tensile samples of commercial Ta alloys T-111 and ASTAR-811C were irradiated to a total neutron fluence (E > 0.1 MeV) in the range (2–4)x1021 n/cm2 (0.39–0.75 dpa) at an irradiation temperature near 900 °C. Tensile testing conducted at room temperature and at 800 °C revealed significant irradiation hardening under all test conditions. Samples that were tensile tested at room temperature exhibited brittle failure, whereas ductility was maintained for elevated temperature testing. The irradiation hardening and embrittlement noted for both alloys was attributed to irradiation-induced dislocation loop formation as confirmed through scanning transmission electron microscopy analysis. Corresponding energy dispersive x-ray spectroscopy revealed radiation-induced segregation of Hf in these loop populations. This Hf enrichment is shown to result in eventual co-precipitation of elongated (Hf,O)-rich precipitates along the dislocation loops. These results show that irradiation hardening is enhanced via irradiation-enhanced precipitation at elevated irradiation temperatures. Consequently, the minimum recommended operating temperature window for Ta alloys should be increased to account for observed hardening/embrittlement at irradiation temperatures as high as 900 °C (1,173 K).
| Original language | English |
|---|---|
| Article number | 154906 |
| Journal | Journal of Nuclear Materials |
| Volume | 591 |
| DOIs | |
| State | Published - Apr 1 2024 |
Funding
Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05–00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05–00OR22725 with the US Department of Energy (DOE). The neutron irradiation of the Ta alloys was performed under the sponsorship of NASA's Project Prometheus and directed by the US Department of Energy/National Nuclear Security Administration (DOE/NNSA) Naval Reactors. Opinions and conclusions drawn by the authors are not endorsed by DOE/NNSA Naval Reactors. A portion of the postirradiation examination tasks in this work was supported by the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07–051D14517 as part of a Nuclear Science User Facilities Rapid Turnaround Experiments under awarded proposals 20–4166 and 21–4331.
| Funders | Funder number |
|---|---|
| NASA's Project Prometheus | |
| U.S. Department of Energy | |
| Office of Nuclear Energy | 21–4331, DE-AC07–051D14517 |
| National Nuclear Security Administration |
Keywords
- Electron microscopy
- Irradiation-hardening
- Mechanical properties
- Post-irradiation examination
- Refractory alloys
- Space-nuclear propulsion
- Tantalum