Heterogeneous dislocation loop formation near grain boundaries in a neutron-irradiated commercial FeCrAl alloy

JOURNAL OF NUCLEAR MATERIALS

卷:483

Article

Field, Kevin G.¹  Briggs, Samuel A.²  Hu, Xunxiang¹  Yamamoto, Yukinori¹  Howard, Richard H.¹  Sridharan, Kumar² 

[1] Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA

[2] Univ Wisconsin, Madison, WI 53703 USA

关键词: FeCrAl;    Accident tolerant;    Phase stability;    Dislocation;    Grain boundary;   

DOI  :  10.1016/j.jnucmat.2016.10.050

来源: Elsevier

【 摘 要 】

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 degrees C have shown post-irradiation microstructures containing dislocation loops and a Cr-rich alpha' 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 degrees 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. (C) 2016 Elsevier B.V. All rights reserved.

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