Abstract
Transmutation-induced precipitation in neutron-irradiated tungsten is an important performance concern for its application as plasma facing material in fusion reactors. In this study, segregation and precipitation of transmutant elements in single crystal and polycrystal tungsten irradiated at 460–1100 °C to 0.02–2.4 displacements per atom (dpa) in the High Flux Isotope Reactor were investigated using transmission electron microscopy. The results indicated that nanoscale W-Re-Os clusters were identified in the low dose regime from 0.02 to 0.44 dpa with irradiation temperature lower than 800 °C while acicular-shape precipitates formed when irradiation dose is higher than 1.5 dpa. A tentative roadmap of the kinetics process of the transmutation-induced precipitation in neutron-irradiated tungsten is presented characterizing the defect features (i.e., W-Re-Os clusters and precipitates) consisting of transmutant elements in tungsten irradiated to various doses. All TEM-visible voids were associated with the acicular-shape precipitates. Voids were formed prior to the formation of acicular-shape precipitates and act as strong trapping sites for mobile species involved in the precipitation together with dislocations. Thermal stability of W-Re-Os clusters was assessed by performing a 2-h anneal at 1200 °C on tungsten irradiated to 0.44 dpa at 705 °C. The kinetics process of transmutant elements and radiation defects are discussed to reveal the underlying mechanisms controlling the formation of precipitates in tungsten.
| Original language | English |
|---|---|
| Pages (from-to) | 51-61 |
| Number of pages | 11 |
| Journal | Acta Materialia |
| Volume | 165 |
| DOIs | |
| State | Published - Feb 15 2019 |
Funding
This work was partially supported by Laboratory Directed R&D funds at ORNL . The research was also sponsored by the US Department of Energy Office of Fusion Energy Science under grant DE-AC05-00OR22725 with UT-Battelle LLC . Strong supports from HFIR and LAMDA staff are greatly appreciated. This work was partly performed at Los Alamos National Laboratory supported by funding from DOE-NE’s Nuclear Technology Research and Development program. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under contract DE-AC52-06NA25396 . This work was partially supported by Laboratory Directed R&D funds at ORNL. The research was also sponsored by the US Department of Energy Office of Fusion Energy Science under grant DE-AC05-00OR22725 with UT-Battelle LLC. Strong supports from HFIR and LAMDA staff are greatly appreciated. This work was partly performed at Los Alamos National Laboratory supported by funding from DOE-NE's Nuclear Technology Research and Development program. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under contract DE-AC52-06NA25396.
Keywords
- Neutron irradiation
- Plasma facing material
- Precipitation
- Transmutation
- Tungsten
