Abstract
FeCrAl alloys are an attractive class of materials for nuclear power applications because of their increased environmental compatibility compared with more traditional nuclear materials. Preliminary studies into the radiation tolerance of FeCrAl alloys under accelerated neutron testing between 300 and 400 °C have shown post-irradiation microstructures containing dislocation loops and a Cr-rich α′ phase. Although these initial studies established the post-irradiation microstructures, there was little to no focus on understanding the influence of pre-irradiation microstructures on this response. In this study, a well-annealed commercial FeCrAl alloy, Alkrothal 720, was neutron irradiated to 1.8 displacements per atom (dpa) at 382 °C and then the effect of random high-angle grain boundaries on the spatial distribution and size of a〈100〉 dislocation loops, a/2〈111〉 dislocation loops, and black dot damage was analyzed using on-zone scanning transmission electron microscopy. Results showed a clear heterogeneous dislocation loop formation with a/2〈111〉 dislocation loops showing an increased number density and size, black dot damage showing a significant number density decrease, and a〈100〉 dislocation loops exhibiting an increased size in the vicinity of the grain boundary. These results suggest the importance of the pre-irradiation microstructure and, specifically, defect sink density spacing to the radiation tolerance of FeCrAl alloys.
Original language | English |
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Pages (from-to) | 54-61 |
Number of pages | 8 |
Journal | Journal of Nuclear Materials |
Volume | 483 |
DOIs | |
State | Published - Jan 1 2017 |
Funding
The authors would like to thank the Irradiated Materials Examination and Testing facility and Low Activation Materials Development and Analysis laboratory staff for their continuing support of this research. Research was sponsored by the Department of Energy (DOE) Office of Nuclear Energy , Advanced Fuel Campaign of the Fuel Cycle R&D program . Neutron irradiation of FeCrAl alloys at the Oak Ridge National Laboratory's HFIR user facility was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, DOE . A portion of support for one of the authors (SAB) was provided by the DOE Office of Nuclear Energy University Programs .
Keywords
- Accident tolerant
- Dislocation
- FeCrAl
- Grain boundary
- Phase stability