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Title: Mechanical properties of neutron-irradiated model and commercial FeCrAl alloys

Abstract

The development and understanding of the mechanical properties of neutron-irradiated FeCrAl alloys is increasingly a critical need as these alloys continue to become more mature for nuclear reactor applications. This study focuses on the mechanical properties of model FeCrAl alloys and of a commercial FeCrAl alloy neutron-irradiated to up to 13.8 displacements per atom (dpa) at irradiation temperatures between 320 and 382 °C. Tensile tests were completed at room temperature and at 320 °C, and a subset of fractured tensile specimens was examined by scanning electron microscopy. Results showed typical radiation hardening and embrittlement indicative of high chromium ferritic alloys with strong chromium composition dependencies at lower doses. At and above 7.0 dpa, the mechanical properties saturated for both the commercial and model FeCrAl alloys, although brittle cleavage fracture was observed at the highest dose in the model FeCrAl alloy with the highest chromium content (18 wt %). Finally, the results suggest the composition and microstructure of FeCrAl alloys plays a critical role in the mechanical response of FeCrAl alloys irradiated near temperatures relevant to light water reactors.

Authors:
ORCiD logo [1]; ORCiD logo [2];  [2]; ORCiD logo [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Wisconsin, Madison, WI (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1351763
Alternate Identifier(s):
OSTI ID: 1419551
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 489; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; FeCrAl; accident tolerant; mechanical properties

Citation Formats

Field, Kevin G., Briggs, Samuel A., Sridharan, Kumar, Howard, Richard H., and Yamamoto, Yukinori. Mechanical properties of neutron-irradiated model and commercial FeCrAl alloys. United States: N. p., 2017. Web. doi:10.1016/j.jnucmat.2017.03.038.
Field, Kevin G., Briggs, Samuel A., Sridharan, Kumar, Howard, Richard H., & Yamamoto, Yukinori. Mechanical properties of neutron-irradiated model and commercial FeCrAl alloys. United States. doi:10.1016/j.jnucmat.2017.03.038.
Field, Kevin G., Briggs, Samuel A., Sridharan, Kumar, Howard, Richard H., and Yamamoto, Yukinori. Tue . "Mechanical properties of neutron-irradiated model and commercial FeCrAl alloys". United States. doi:10.1016/j.jnucmat.2017.03.038. https://www.osti.gov/servlets/purl/1351763.
@article{osti_1351763,
title = {Mechanical properties of neutron-irradiated model and commercial FeCrAl alloys},
author = {Field, Kevin G. and Briggs, Samuel A. and Sridharan, Kumar and Howard, Richard H. and Yamamoto, Yukinori},
abstractNote = {The development and understanding of the mechanical properties of neutron-irradiated FeCrAl alloys is increasingly a critical need as these alloys continue to become more mature for nuclear reactor applications. This study focuses on the mechanical properties of model FeCrAl alloys and of a commercial FeCrAl alloy neutron-irradiated to up to 13.8 displacements per atom (dpa) at irradiation temperatures between 320 and 382 °C. Tensile tests were completed at room temperature and at 320 °C, and a subset of fractured tensile specimens was examined by scanning electron microscopy. Results showed typical radiation hardening and embrittlement indicative of high chromium ferritic alloys with strong chromium composition dependencies at lower doses. At and above 7.0 dpa, the mechanical properties saturated for both the commercial and model FeCrAl alloys, although brittle cleavage fracture was observed at the highest dose in the model FeCrAl alloy with the highest chromium content (18 wt %). Finally, the results suggest the composition and microstructure of FeCrAl alloys plays a critical role in the mechanical response of FeCrAl alloys irradiated near temperatures relevant to light water reactors.},
doi = {10.1016/j.jnucmat.2017.03.038},
journal = {Journal of Nuclear Materials},
number = C,
volume = 489,
place = {United States},
year = {Tue Mar 28 00:00:00 EDT 2017},
month = {Tue Mar 28 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
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Citation Metrics:
Cited by: 5works
Citation information provided by
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  • In this paper, Alkrothal 720 and Kanthal APMT™, two commercial FeCrAl alloys, were neutron irradiated up to damage doses of 7.0 displacements per atom (dpa) in the temperature range of 320 to 382 °C to characterize the α' precipitation in these alloys using small-angle neutron scattering. Both alloys exhibited α' precipitation. Kanthal APMT™ exhibited higher number densities and volume fraction, a result attributed to its higher Cr content compared with Alkrothal 720. Finally, trends observed as a function of damage dose (dpa) are consistent with literature trends for both FeCr and FeCrAl alloys
  • Here, FeCrAl alloys are currently under consideration for accident-tolerant fuel cladding applications in light water reactors owing to their superior high-temperature oxidation and corrosion resistance compared to the Zr-based alloys currently employed. However, their performance could be limited by precipitation of a Cr-rich α' phase that tends to embrittle high-Cr ferritic Fe-based alloys. In this study, four FeCrAl model alloys with 10–18 at.% Cr and 5.8–9.3 at.% Al were neutron-irradiated to nominal damage doses up to 7.0 displacements per atom at a target temperature of 320 °C. Small angle neutron scattering techniques were coupled with atom probe tomography to assessmore » the composition and morphology of the resulting α' precipitates. It was demonstrated that Al additions partially destabilize the α' phase, generally resulting in precipitates with lower Cr contents when compared with binary Fe-Cr systems. The precipitate morphology evolution with dose exhibited a transient coarsening regime akin to previously observed behavior in aged Fe-Cr alloys. Similar behavior to predictions of the LSW/UOKV models suggests that α' precipitation in irradiated FeCrAl is a diffusion-limited process with coarsening mechanisms similar to those in thermally aged high-Cr ferritic alloys.« less
  • FeCrAl alloys are an attractive materials class for nuclear power applications due to their increased environmental compatibility over more traditional nuclear materials. Preliminary studies into the radiation tolerance of FeCrAl alloys under accelerated neutron testing between 300-400 °C have shown post-irradiation microstructures containing dislocation loops and Cr-rich ' phase. Although these initial works established the post-irradiation microstructures, little to no focus was applied towards the influence of pre-irradiation microstructures on this response. Here, a well annealed commercial FeCrAl alloy, Alkrothal 720, was neutron irradiated to 1.8 dpa at 382 °C and then the role of random high angle grain boundariesmore » on the spatial distribution and size of dislocation loops, dislocation loops, and black dot damage was analyzed using on-zone scanning transmission electron microscopy. Results showed a clear heterogeneous dislocation loop formation with dislocation loops showing an increased number density and size, black dot damage showing a significant number density decrease, and an increased size of dislocation loops in the vicinity directly adjacent to the grain boundary. Lastly, these results suggest the importance of the pre-irradiation microstructure on the radiation tolerance of FeCrAl alloys.« less