Abstract
Microstructures of T91 neutron irradiated in the BOR60 reactor at five temperatures between 376 °C and 524 °C to doses between 15.4 and 35.1 dpa were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and atom probe tomography (APT). Type a<100> dislocation loops were observed at 376–415 °C and network dislocations dominated at 460 °C and 524 °C. Cavities appeared in a bimodal distribution with a high density of small bubbles less than 2 nm at irradiation temperatures between 376 °C and 415 °C. Small bubbles were also observed at 460 °C and 524 °C but cavities greater than 2 nm were absent. Enrichment of Cr, Ni, and Si at the grain boundary was observed at all irradiation temperatures. Radiation-induced segregation (RIS) of Cr, Ni and Si appeared to saturate at 17.1 dpa and 376 °C. The temperature dependence of RIS of Cr, Ni and Si at the grain boundary, which showed a peak Cr enrichment temperature of 460 °C and a lower peak Ni and Si enrichment temperature of ∼400 °C, was consistent with observations of RIS of Cr in proton irradiated T91, suggesting that the same RIS mechanism may also apply to BOR60 irradiated T91. G-phase and Cu-rich precipitates were observed at 376–415 °C but were absent at 460 °C and 524 °C. The absence of G-phase at 524 °C could be related to the minimal segregation of Ni and Si in that condition.
| Original language | English |
|---|---|
| Pages (from-to) | 122-134 |
| Number of pages | 13 |
| Journal | Journal of Nuclear Materials |
| Volume | 504 |
| DOIs | |
| State | Published - Jun 2018 |
| Externally published | Yes |
Funding
The authors gratefully acknowledge Drs. M.J. Hackett, B.A. Hilton, and C. Xu at TerraPower, LLC and Dr. T. Saleh at Los Alamos National Laboratory for providing on-going support of the BOR60 irradiation campaign. The authors would also like to thank the Irradiated Materials Examination and Testing (IMET) facility and LAMDA laboratory staff for their continuing support of this research. Primary support for this research was provided by Department of Energy under contract DE-NE0000639 . The atom probe tomography work was supported by the Engineering and Physical Sciences Research Council (EPSRC) funding under contract EP/L025817/1 and EP/M022803/1 . Electron microscopy characterization using ORNL's LAMDA facility was supported by the Department of Energy, Office of Nuclear Energy, under DOE Idaho Operations Office Contract DE-AC07-051D14517 as part of a Nuclear Science User Facilities experiment. This research was performed, in part, using instrumentation (FEI Talos) provided by the Department of Energy, Office of Nuclear Energy, Nuclear Technology R&D (formerly Fuel Cycle R&D) Program, and the Nuclear Science User Facilities.
| Funders | Funder number |
|---|---|
| Nuclear Technology R&D | |
| U.S. Department of Energy | DE-AC07-051D14517, DE-NE0000639 |
| Office of Nuclear Energy | |
| Engineering and Physical Sciences Research Council | EP/J013501/1, EP/L025817/1, EP/P005640/1, EP/M022803/1 |
Keywords
- Microstructure
- Radiation-induced precipitates
- Radiation-induced segregation
- Swelling