NSUF 26-5649: SEM and TEM Characterization of Phase Reverted U-10Mo Alloys Neutron Irradiated to Mid Dose Sub-Eutectoid Temperatures
U-Mo fuels are promising candidates for advanced reactors due to their fuel efficiency and irradiation resistance, the latter due to isotropic swelling exhibited by the predominant γ-phase. However, γ-UMo is metastable at subeutectoid temperatures, and the thermodynamically-stable the α+γ' phases, have poor irradiation stability. The transformations between the γ and the α+γ' phases are known to be dictated by thermal diffusion and irradiation, with thermal diffusion promoting the γ→α+γ' phase decomposition and irradiation promoting the α+γ^'→γ phase reversal. While mechanisms driving phase decomposition has been studied extensively, phase reversal remains poorly understood. Recent XRD investigations of U-10Mo specimens neutron irradiated at a constant fission rate and temperature have demonstrated peculiar trends in changes in the phase composition with increasing irradiation dose, indicating an unknown third mechanism involved, possibly dependent on the dose. The proposed study will investigate five higher dose specimens that have undergone phase reversal via SEM and TEM to verify the mechanism(s) involved by examining the microstructural features. Furthermore, this study will also reveal how the fission gas bubbles observed near α/γ' phase boundaries in decomposed regions resolves and re-organizes after phase reversal. Jet-polishing will be used to prepare the specimens. Microstructural characterization will be performed using SEM (SE and BSE modes) and using TEM ( BF and HAADF modes). SAED patterns and EDS maps will be obtained for targeted phase identification and to capture any compositional changes. The initial jet polishing will be performed at the EML, INL (~10 hours). The SEM and SEM-EDS will be performed on the Tescan LYRA-3GM at the EML (~24.5 hours). Finally, TEM characterization will be performed on the FEI Titan STEM at IMCL, INL (~45.5 hours). Overall, the entire study will span 2 weeks.
Additional Info
| Field | Value |
|---|---|
| Awarded Institution | Purdue University |
| DOI | 10.46936/NSUF/60017663 |
| Embargo End Date | 2028-04-22 |
| Facility Tech Lead | Noé Morales |
| NSUF Call | FY 2026 RTE 1st Call |
| PI | Sukanya Majumder |
| PIE Facilities | Irradiated Materials Characterization Laboratory, Electron Microscopy Laboratory |
| Prep Facilities | Irradiated Materials Characterization Laboratory, Electron Microscopy Laboratory |
| Project Member | Assoc. Prof. Maria Okuniewski, Associate Professor - Purdue University (https://orcid.org/0000-0003-3498-6827) |
| Project Member | Ms. Sukanya Majumder, Graduare Research Assistant - Purdue University (https://orcid.org/0000-0002-0354-9870) |
| Project Type | RTE |
| Sample Identifiers | 11655,9701,9702,9712,9713,9761,9513 |