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In situ TEM investigation of irradiation-induced defect formation in cold spray Cr coatings for accident tolerant fuel applications
Journal of Nuclear Materials 512 (2018) 320e323
Contents lists available at ScienceDirect
Journal of Nuclear Materials journal homepage: www.elsevier.com/locate/jnucmat
In situ TEM investigation of irradiation-induced defect formation in cold spray Cr coatings for accident tolerant fuel applications Benjamin R. Maier a, *, Hwasung Yeom a, Greg Johnson a, Tyler Dabney a, Jing Hu b, Peter Baldo b, Meimei Li b, Kumar Sridharan a a b
University of Wisconsin e Madison Engineering Physics, 1500 Engineering Dr, Madison, WI, 53706, USA Intermediate Voltage Electron Microscope, Argonne National Laboratory, 9700 Cass Avenue, Lemont, IL, 60439, USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 September 2018 Received in revised form 13 October 2018 Accepted 15 October 2018 Available online 16 October 2018
The first in-situ ion irradiation and transmission electron microscopy (TEM) of cold spray deposited Cr coatings was performed at the Intermediate Voltage Electron Microscope (IVEM) facility at Argonne National Laboratory for preliminary investigation into the radiation damage tolerance of these materials for use in accident tolerance fuel cladding. The severely plastically deformed microstructure of the cold spray deposited Cr delayed the onset and growth of radiation induced defects when compared to an annealed coating simulating bulk Cr. Evidence to support this conclusion was based on defect density and defect size measurements of TEM images obtained at different irradiation intervals. © 2018 Elsevier B.V. All rights reserved.
1. Summary of experimental results Current Zr-alloy fuel claddings have been successfully used for over four decades in light water reactors (LWRs). However, the Fukushima-Daiichi accident in 2011 has raised concerns over the durability of Zr-alloy as the cladding material in loss-of-coolant accident (LOCA) or beyond-design-basis accident (BDBA) scenarios due to its profuse exothermic oxidation with air/steam and the associated hydrogen gas generation [1e3]. Significant interest in fabrication of fuel with increased accident tolerance (ATF) for LWRs has led to the development of cold spray deposited Cr coatings on currently used Zr-alloys. In earlier studies we have shown that cold spray Cr coatings have improved performance under accident conditions compared to uncoated Zr-alloys [4,5]. However, the radiation damage response of these materials has yet to be investigated. In the cold spray process, powder particles of the coating material are accelerated to high velocities (2e4 Mach) on to the surface of a substrate using a pre-heated, pressurized, inert gas and specially engineered nozzle [6]. The particle temperature is low, and deposition occurs in solid-state. The coating formation on the substrate surface occurs by severe solid-state plastic deformation of
* Corresponding author. E-mail address: [email protected] (B.R. Maier). https://doi.org/10.1016/j.jnucmat.2018.10.023 0022-3115/© 2018 Elsevier B.V. All rights reserved.
the particles and associated adiabatic shear mechanisms both between the particles as well as the particles and the substrate [7]. Compositional and phase purity of the powders is retained in the coating due to the low process temperature and the solid-state nature of the deposition process. The coatings are generally dense and free of oxidation and this coupled with the high deposition rates, solid state deposition, and atmospheric environment operation make cold spray amenable to large-scale commercial manufacturing, particularly for reactive pure Cr metal on Zr-alloys for ATF. The cold spray Cr coating selected for this study was produced for preliminary screening of cold spray Cr on Zr-alloys as a lead concept for ATF application in LWRs [4]. Additionally, a portion of the as-deposited sample was sectioned and separately annealed at 800 C for 8 h for comparison with the as-deposited condition. Annealing the deposited coating under these conditions would remove deformation effects from the cold spray process and produce a material representative of bulk annealed Cr. The annealed cold spray Cr coating is referred to as bulk Cr henceforth. A focused ion beam (FIB) and lift-out needle were used to extract a TEM lamella from the surfaces of the Cr coating and bulk Cr, with subsequent FIB milling steps to thin the lamella to achieve electron transparency. The final sample thickness was acquired using electron energy loss spectroscopy (EELS) where the log ratio of the total number of electrons in the spectrum to the electrons in the zero loss peak was measured to determine sample thickness in terms of
B.R. Maier et al. / Journal of Nuclear Materials 512 (2018) 320e323
321
Fig. 1. TEM images of the (a) as-deposited (cold sprayed) Cr sample with elongated grains and dense dislocation networks and (b) bulk Cr coating with more equiaxed grains mostly free of defect contrast.
Fig. 2. TEM images of the defect production in bulk (annealed) Cr (a) initial defects in the starting unirradiated material possibly from FIB sample preparation, (b) immediate formation of dislocation loop type defects at 0.1 dpa, and (c) a significant number of defects at 3 dpa.
electron mean free path lengths. The number of mean free path lengths measured using this ratio technique was multiplied by a measure mean free path length taken from Iakoubovskii and Mitsuishi [8]. The sample thickness was determined to be 209.3 ± 22.9 nm for the as-deposited sample and 211.6 ± 8.2 nm for the bulk Cr, respectively. This information was used to evaluate the volumetric number density of dislocation loops formed during ion irradiation. Transmission electron microscopy (TEM) images in Fig. 1 of the (a) as-deposited Cr coating show elongated grains with dense dislocation structures in each grain due the severe plastic deformation from the cold spray process. Comparatively, the bulk Cr in Fig. 1(b) has more equiaxed grains with fewer deformation induced defects. It has been proposed and shown experimentally that in severely plastically deformed (SPD) materials pre-existing deformation-induced features act as sinks that resist radiation-induced damage [9]. Similarly, nanocrystalline materials have a larger volume fraction of grain boundaries that act sinks for radiation defects, inhibiting formation of larger radiation defect clusters [10].
Therefore, the as-deposited cold spray Cr coating with defects and fine subgrain structure formed due to local dynamic recrystallization effects should resist radiation damage better than the bulk Cr. The as-deposited and bulk Cr samples were irradiated using 1 MeV Krþ2 ions at a flux of 6.3 1011 ions/s (9.6 104 displacements per atom/s or dpa/s) and a temperature of 320 C while being examined in-situ with TEM at the Intermediate Voltage Electron Microscope (IVEM) at Argonne National Laboratory. A two-beam bright field condition with g vector in the <011> orientation was used to visualize the defects. The bulk Cr sample had few defects before irradiation as shown in Fig. 2(a), but formation of irradiation induced defects was immediately apparent with many more black spots becoming immediately visible at 0.1 dpa, as shown in Fig. 2(b). These black spot representing small dislocation loops coalesced into larger features and increased in number density when the bulk Cr was irradiated to 3 dpa, as shown in Fig. 2(c). Comparatively, the as-deposited Cr sample also had a few small spot defects with dislocation lines resulting from the severe deformation of the cold spray process, as shown in Fig. 3(a).
Fig. 3. TEM images of the (a) as-deposited Cr coating, (b) initial noticeable formation of small defects occurs only at 0.7 dpa, and are (c) larger size and density at 3 dpa, though smaller in size and number density than observed in the bulk Cr shown in Fig. 2(c).
322
B.R. Maier et al. / Journal of Nuclear Materials 512 (2018) 320e323
Fig. 4. Quantitative evaluation of irradiation-induced defects in as-deposited (cold sprayed) Cr and annealed bulk Cr showing, (a) lower defect number density in as-deposited Cr coating compared to bulk Cr and (b) slightly lower average loop size in as-deposited Cr coating compared to bulk Cr. These results are attributed to deformation induced defects in the as-cold spray deposited coating prior to irradiation which acted as strong sinks from point defects formed during ion irradiation.
Irradiation-induced defects did not become visible until 0.5 dpa (image not shown but was observed in in-situ TEM video), and began to form in noticeable density only at 0.7 dpa, as shown in Fig. 3(b). The defects were not as prevalent as in the bulk Cr coating at a similar dose level. Finally, at 3 dpa many more defects are visible, as shown in Fig. 3(c), smaller in size and at a lower frequency than those observed at 3dpa in the bulk Cr sample. The lack of defect formation in the as-deposited Cr coating compared to the bulk Cr coating is attributed to the greater volume fraction of sinks (e.g. grain boundaries and dislocation networks) in the severely plastically deformed cold spray Cr coating. The two-beam bright field TEM images in Figs. 2 and 3 for the bulk Cr and as-deposited Cr coating respectively, were analyzed to quantify the number of radiation induced dislocation loops. Defects were counted using ImageJ where line regions of interest (ROI's) were drawn across the defect diameters. The number of ROI's was summed and divided by the analysis area which produced the defect density for each condition, Fig. 4(a). The average defect diameter was calculated from the average ROI length, Fig. 4(b). Residual defects from the FIB milling sample preparation were present in both samples as evidenced by defect observation at 0 dpa (before irradiation), with slightly fewer defects in the asdeposited samples. It should be noted that the same procedure (FIB currents and milling times) was used to fabricate both types of samples, meaning the as-deposited (cold sprayed) sample possibly tolerated FIB damage more readily than the annealed bulk Cr samples. The number of spot type defects in the bulk sample at 0.1 dpa is similar to the number of the defects in the as-deposited Cr sample at 0.7 dpa, providing further evidence that the cold spray material was more resistant to irradiation-induced defect formation. Similarly, when both conditions of Cr were irradiated to 3 dpa, the as-deposited Cr still had a statistically significant lower defect density. Both types of samples show a trend of the defect formation leveling off as new point defects produced from the ion bombardment would be increasingly absorbed by the existing defects, thus leading to coarsening the existing loops (i.e. increasing loop size) in favor of new loop defect formation [11]. The size of the loops did not change dramatically during irradiation for the as-deposited Cr sample and only slightly increased in size from 0.7 dpa to 3 dpa as shown in Fig. 4. The average loop size in the bulk sample increased significantly during the irradiation, particularly during the first 0.1 dpa of exposure, as the existing
loops absorbed radiation point defects. The bulk Cr sample also had an average defect loop size 60% larger than the as-deposited Cr coating after both samples were irradiated to 3dpa. This larger average loop size provides additional evidence that the asdeposited condition was more effective at absorbing defects produced from ion irradiation since the defect loops grew to be much larger in the bulk sample. The first ion irradiation results of cold spray deposited Cr are presented in this paper. The initial in-situ ion irradiation and TEM experiments suggest that the deformation induced defects do in fact absorb some of the radiation damage. This was evidenced by in-situ observation of a lower defect number density at comparable dpa levels and smaller loop sizes at medium dpa levels in the asdeposited Cr compared to the bulk annealed Cr. Acknowledgments This work is partially sponsored by the U.S. Department of Energy, Office of Nuclear Energy, under grant number DE-NE000822. The authors would like to thank personnel from Westinghouse Electric Company particularly Javier Romero, Jorie Walters, and Peng Xu for their support in this work. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.jnucmat.2018.10.023. References [1] G. Sabol, R. Comstock, R. Weiner, P. Larouere, R. Stanutz, In-reactor corrosion performance of ZIRLOTM and zircaloy-4, in: React. Corros. Perform. ZIRLOTM Zircaloy-4, 1994. [2] B.A. Pint, K.A. Terrani, Y. Yamamoto, L.L. Snead, Material selection for accident tolerant fuel cladding, Metall. Mater. Trans. E. 2 (2015) 190e196, https:// doi.org/10.1007/s40553-015-0056-7. [3] S.J. Zinkle, K.A. Terrani, J.C. Gehin, L.J. Ott, L.L. Snead, Accident tolerant fuels for LWRs: a perspective, J. Nucl. Mater. 448 (2014) 374e379, https://doi.org/ 10.1016/j.jnucmat.2013.12.005. [4] B. Maier, H. Yeom, G. Johnson, T. Dabney, J. Walters, J. Romero, H. Shah, P. Xu, K. Sridharan, Development of cold spray coatings for accident-tolerant fuel cladding in light water reactors, JOM 70 (2018) 198e202, https://doi.org/ 10.1007/s11837-017-2643-9. [5] H. Shah, J. Romero, P. Xu, K. Sridharan, B.R. Maier, G. Johnson, J. Walters, T. Dabney, H. Yeom, Development of surface coatings for enhanced accident tolerant fuel, in: Jeju Island, South Korea, 2017. €rtner, H. Assadi, H. Kreye, Development of a generalized [6] T. Schmidt, F. Ga
B.R. Maier et al. / Journal of Nuclear Materials 512 (2018) 320e323 parameter window for cold spray deposition, Acta Mater. 54 (2006) 729e742, https://doi.org/10.1016/j.actamat.2005.10.005. [7] H. Assadi, F. G€ artner, T. Stoltenhoff, H. Kreye, Bonding mechanism in cold gas spraying, Acta Mater. 51 (2003) 4379e4394, https://doi.org/10.1016/S13596454(03)00274-X. [8] K. Iakoubovskii, K. Mitsuishi, Y. Nakayama, K. Furuya, Mean free path of inelastic electron scattering in elemental solids and oxides using transmission electron microscopy: atomic number dependent oscillatory behavior, Phys. Rev. B 77 (2008), https://doi.org/10.1103/PhysRevB.77.104102. [9] J.M.K. Wiezorek, M.A. Gordillo, M.A. Kirk, P.M. Baldo, Microstructural evolution of high-strain-rate severe plastic deformation processed 316L during Kr
323
ion irradiation and elevated temperature exposures, Microsc. Microanal. Camb. 22 (2016) 1484e1485. https://doi.org/10.1017/S1431927616008266. [10] G.A. Vetterick, J. Gruber, P.K. Suri, J.K. Baldwin, M.A. Kirk, P. Baldo, Y.Q. Wang, A. Misra, G.J. Tucker, M.L. Taheri, Achieving radiation tolerance through nonequilibrium grain boundary structures, Sci. Rep. 7 (2017) 12275, https:// doi.org/10.1038/s41598-017-12407-2. [11] J.C. Haley, S.A. Briggs, P.D. Edmondson, K. Sridharan, S.G. Roberts, S. LozanoPerez, K.G. Field, Dislocation loop evolution during in-situ ion irradiation of model FeCrAl alloys, Acta Mater. 136 (2017) 390e401, https://doi.org/ 10.1016/j.actamat.2017.07.011.
Contents lists available at ScienceDirect
Journal of Nuclear Materials journal homepage: www.elsevier.com/locate/jnucmat
In situ TEM investigation of irradiation-induced defect formation in cold spray Cr coatings for accident tolerant fuel applications Benjamin R. Maier a, *, Hwasung Yeom a, Greg Johnson a, Tyler Dabney a, Jing Hu b, Peter Baldo b, Meimei Li b, Kumar Sridharan a a b
University of Wisconsin e Madison Engineering Physics, 1500 Engineering Dr, Madison, WI, 53706, USA Intermediate Voltage Electron Microscope, Argonne National Laboratory, 9700 Cass Avenue, Lemont, IL, 60439, USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 September 2018 Received in revised form 13 October 2018 Accepted 15 October 2018 Available online 16 October 2018
The first in-situ ion irradiation and transmission electron microscopy (TEM) of cold spray deposited Cr coatings was performed at the Intermediate Voltage Electron Microscope (IVEM) facility at Argonne National Laboratory for preliminary investigation into the radiation damage tolerance of these materials for use in accident tolerance fuel cladding. The severely plastically deformed microstructure of the cold spray deposited Cr delayed the onset and growth of radiation induced defects when compared to an annealed coating simulating bulk Cr. Evidence to support this conclusion was based on defect density and defect size measurements of TEM images obtained at different irradiation intervals. © 2018 Elsevier B.V. All rights reserved.
1. Summary of experimental results Current Zr-alloy fuel claddings have been successfully used for over four decades in light water reactors (LWRs). However, the Fukushima-Daiichi accident in 2011 has raised concerns over the durability of Zr-alloy as the cladding material in loss-of-coolant accident (LOCA) or beyond-design-basis accident (BDBA) scenarios due to its profuse exothermic oxidation with air/steam and the associated hydrogen gas generation [1e3]. Significant interest in fabrication of fuel with increased accident tolerance (ATF) for LWRs has led to the development of cold spray deposited Cr coatings on currently used Zr-alloys. In earlier studies we have shown that cold spray Cr coatings have improved performance under accident conditions compared to uncoated Zr-alloys [4,5]. However, the radiation damage response of these materials has yet to be investigated. In the cold spray process, powder particles of the coating material are accelerated to high velocities (2e4 Mach) on to the surface of a substrate using a pre-heated, pressurized, inert gas and specially engineered nozzle [6]. The particle temperature is low, and deposition occurs in solid-state. The coating formation on the substrate surface occurs by severe solid-state plastic deformation of
* Corresponding author. E-mail address: [email protected] (B.R. Maier). https://doi.org/10.1016/j.jnucmat.2018.10.023 0022-3115/© 2018 Elsevier B.V. All rights reserved.
the particles and associated adiabatic shear mechanisms both between the particles as well as the particles and the substrate [7]. Compositional and phase purity of the powders is retained in the coating due to the low process temperature and the solid-state nature of the deposition process. The coatings are generally dense and free of oxidation and this coupled with the high deposition rates, solid state deposition, and atmospheric environment operation make cold spray amenable to large-scale commercial manufacturing, particularly for reactive pure Cr metal on Zr-alloys for ATF. The cold spray Cr coating selected for this study was produced for preliminary screening of cold spray Cr on Zr-alloys as a lead concept for ATF application in LWRs [4]. Additionally, a portion of the as-deposited sample was sectioned and separately annealed at 800 C for 8 h for comparison with the as-deposited condition. Annealing the deposited coating under these conditions would remove deformation effects from the cold spray process and produce a material representative of bulk annealed Cr. The annealed cold spray Cr coating is referred to as bulk Cr henceforth. A focused ion beam (FIB) and lift-out needle were used to extract a TEM lamella from the surfaces of the Cr coating and bulk Cr, with subsequent FIB milling steps to thin the lamella to achieve electron transparency. The final sample thickness was acquired using electron energy loss spectroscopy (EELS) where the log ratio of the total number of electrons in the spectrum to the electrons in the zero loss peak was measured to determine sample thickness in terms of
B.R. Maier et al. / Journal of Nuclear Materials 512 (2018) 320e323
321
Fig. 1. TEM images of the (a) as-deposited (cold sprayed) Cr sample with elongated grains and dense dislocation networks and (b) bulk Cr coating with more equiaxed grains mostly free of defect contrast.
Fig. 2. TEM images of the defect production in bulk (annealed) Cr (a) initial defects in the starting unirradiated material possibly from FIB sample preparation, (b) immediate formation of dislocation loop type defects at 0.1 dpa, and (c) a significant number of defects at 3 dpa.
electron mean free path lengths. The number of mean free path lengths measured using this ratio technique was multiplied by a measure mean free path length taken from Iakoubovskii and Mitsuishi [8]. The sample thickness was determined to be 209.3 ± 22.9 nm for the as-deposited sample and 211.6 ± 8.2 nm for the bulk Cr, respectively. This information was used to evaluate the volumetric number density of dislocation loops formed during ion irradiation. Transmission electron microscopy (TEM) images in Fig. 1 of the (a) as-deposited Cr coating show elongated grains with dense dislocation structures in each grain due the severe plastic deformation from the cold spray process. Comparatively, the bulk Cr in Fig. 1(b) has more equiaxed grains with fewer deformation induced defects. It has been proposed and shown experimentally that in severely plastically deformed (SPD) materials pre-existing deformation-induced features act as sinks that resist radiation-induced damage [9]. Similarly, nanocrystalline materials have a larger volume fraction of grain boundaries that act sinks for radiation defects, inhibiting formation of larger radiation defect clusters [10].
Therefore, the as-deposited cold spray Cr coating with defects and fine subgrain structure formed due to local dynamic recrystallization effects should resist radiation damage better than the bulk Cr. The as-deposited and bulk Cr samples were irradiated using 1 MeV Krþ2 ions at a flux of 6.3 1011 ions/s (9.6 104 displacements per atom/s or dpa/s) and a temperature of 320 C while being examined in-situ with TEM at the Intermediate Voltage Electron Microscope (IVEM) at Argonne National Laboratory. A two-beam bright field condition with g vector in the <011> orientation was used to visualize the defects. The bulk Cr sample had few defects before irradiation as shown in Fig. 2(a), but formation of irradiation induced defects was immediately apparent with many more black spots becoming immediately visible at 0.1 dpa, as shown in Fig. 2(b). These black spot representing small dislocation loops coalesced into larger features and increased in number density when the bulk Cr was irradiated to 3 dpa, as shown in Fig. 2(c). Comparatively, the as-deposited Cr sample also had a few small spot defects with dislocation lines resulting from the severe deformation of the cold spray process, as shown in Fig. 3(a).
Fig. 3. TEM images of the (a) as-deposited Cr coating, (b) initial noticeable formation of small defects occurs only at 0.7 dpa, and are (c) larger size and density at 3 dpa, though smaller in size and number density than observed in the bulk Cr shown in Fig. 2(c).
322
B.R. Maier et al. / Journal of Nuclear Materials 512 (2018) 320e323
Fig. 4. Quantitative evaluation of irradiation-induced defects in as-deposited (cold sprayed) Cr and annealed bulk Cr showing, (a) lower defect number density in as-deposited Cr coating compared to bulk Cr and (b) slightly lower average loop size in as-deposited Cr coating compared to bulk Cr. These results are attributed to deformation induced defects in the as-cold spray deposited coating prior to irradiation which acted as strong sinks from point defects formed during ion irradiation.
Irradiation-induced defects did not become visible until 0.5 dpa (image not shown but was observed in in-situ TEM video), and began to form in noticeable density only at 0.7 dpa, as shown in Fig. 3(b). The defects were not as prevalent as in the bulk Cr coating at a similar dose level. Finally, at 3 dpa many more defects are visible, as shown in Fig. 3(c), smaller in size and at a lower frequency than those observed at 3dpa in the bulk Cr sample. The lack of defect formation in the as-deposited Cr coating compared to the bulk Cr coating is attributed to the greater volume fraction of sinks (e.g. grain boundaries and dislocation networks) in the severely plastically deformed cold spray Cr coating. The two-beam bright field TEM images in Figs. 2 and 3 for the bulk Cr and as-deposited Cr coating respectively, were analyzed to quantify the number of radiation induced dislocation loops. Defects were counted using ImageJ where line regions of interest (ROI's) were drawn across the defect diameters. The number of ROI's was summed and divided by the analysis area which produced the defect density for each condition, Fig. 4(a). The average defect diameter was calculated from the average ROI length, Fig. 4(b). Residual defects from the FIB milling sample preparation were present in both samples as evidenced by defect observation at 0 dpa (before irradiation), with slightly fewer defects in the asdeposited samples. It should be noted that the same procedure (FIB currents and milling times) was used to fabricate both types of samples, meaning the as-deposited (cold sprayed) sample possibly tolerated FIB damage more readily than the annealed bulk Cr samples. The number of spot type defects in the bulk sample at 0.1 dpa is similar to the number of the defects in the as-deposited Cr sample at 0.7 dpa, providing further evidence that the cold spray material was more resistant to irradiation-induced defect formation. Similarly, when both conditions of Cr were irradiated to 3 dpa, the as-deposited Cr still had a statistically significant lower defect density. Both types of samples show a trend of the defect formation leveling off as new point defects produced from the ion bombardment would be increasingly absorbed by the existing defects, thus leading to coarsening the existing loops (i.e. increasing loop size) in favor of new loop defect formation [11]. The size of the loops did not change dramatically during irradiation for the as-deposited Cr sample and only slightly increased in size from 0.7 dpa to 3 dpa as shown in Fig. 4. The average loop size in the bulk sample increased significantly during the irradiation, particularly during the first 0.1 dpa of exposure, as the existing
loops absorbed radiation point defects. The bulk Cr sample also had an average defect loop size 60% larger than the as-deposited Cr coating after both samples were irradiated to 3dpa. This larger average loop size provides additional evidence that the asdeposited condition was more effective at absorbing defects produced from ion irradiation since the defect loops grew to be much larger in the bulk sample. The first ion irradiation results of cold spray deposited Cr are presented in this paper. The initial in-situ ion irradiation and TEM experiments suggest that the deformation induced defects do in fact absorb some of the radiation damage. This was evidenced by in-situ observation of a lower defect number density at comparable dpa levels and smaller loop sizes at medium dpa levels in the asdeposited Cr compared to the bulk annealed Cr. Acknowledgments This work is partially sponsored by the U.S. Department of Energy, Office of Nuclear Energy, under grant number DE-NE000822. The authors would like to thank personnel from Westinghouse Electric Company particularly Javier Romero, Jorie Walters, and Peng Xu for their support in this work. Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.jnucmat.2018.10.023. References [1] G. Sabol, R. Comstock, R. Weiner, P. Larouere, R. Stanutz, In-reactor corrosion performance of ZIRLOTM and zircaloy-4, in: React. Corros. Perform. ZIRLOTM Zircaloy-4, 1994. [2] B.A. Pint, K.A. Terrani, Y. Yamamoto, L.L. Snead, Material selection for accident tolerant fuel cladding, Metall. Mater. Trans. E. 2 (2015) 190e196, https:// doi.org/10.1007/s40553-015-0056-7. [3] S.J. Zinkle, K.A. Terrani, J.C. Gehin, L.J. Ott, L.L. Snead, Accident tolerant fuels for LWRs: a perspective, J. Nucl. Mater. 448 (2014) 374e379, https://doi.org/ 10.1016/j.jnucmat.2013.12.005. [4] B. Maier, H. Yeom, G. Johnson, T. Dabney, J. Walters, J. Romero, H. Shah, P. Xu, K. Sridharan, Development of cold spray coatings for accident-tolerant fuel cladding in light water reactors, JOM 70 (2018) 198e202, https://doi.org/ 10.1007/s11837-017-2643-9. [5] H. Shah, J. Romero, P. Xu, K. Sridharan, B.R. Maier, G. Johnson, J. Walters, T. Dabney, H. Yeom, Development of surface coatings for enhanced accident tolerant fuel, in: Jeju Island, South Korea, 2017. €rtner, H. Assadi, H. Kreye, Development of a generalized [6] T. Schmidt, F. Ga
B.R. Maier et al. / Journal of Nuclear Materials 512 (2018) 320e323 parameter window for cold spray deposition, Acta Mater. 54 (2006) 729e742, https://doi.org/10.1016/j.actamat.2005.10.005. [7] H. Assadi, F. G€ artner, T. Stoltenhoff, H. Kreye, Bonding mechanism in cold gas spraying, Acta Mater. 51 (2003) 4379e4394, https://doi.org/10.1016/S13596454(03)00274-X. [8] K. Iakoubovskii, K. Mitsuishi, Y. Nakayama, K. Furuya, Mean free path of inelastic electron scattering in elemental solids and oxides using transmission electron microscopy: atomic number dependent oscillatory behavior, Phys. Rev. B 77 (2008), https://doi.org/10.1103/PhysRevB.77.104102. [9] J.M.K. Wiezorek, M.A. Gordillo, M.A. Kirk, P.M. Baldo, Microstructural evolution of high-strain-rate severe plastic deformation processed 316L during Kr
323
ion irradiation and elevated temperature exposures, Microsc. Microanal. Camb. 22 (2016) 1484e1485. https://doi.org/10.1017/S1431927616008266. [10] G.A. Vetterick, J. Gruber, P.K. Suri, J.K. Baldwin, M.A. Kirk, P. Baldo, Y.Q. Wang, A. Misra, G.J. Tucker, M.L. Taheri, Achieving radiation tolerance through nonequilibrium grain boundary structures, Sci. Rep. 7 (2017) 12275, https:// doi.org/10.1038/s41598-017-12407-2. [11] J.C. Haley, S.A. Briggs, P.D. Edmondson, K. Sridharan, S.G. Roberts, S. LozanoPerez, K.G. Field, Dislocation loop evolution during in-situ ion irradiation of model FeCrAl alloys, Acta Mater. 136 (2017) 390e401, https://doi.org/ 10.1016/j.actamat.2017.07.011.