Microstructural evolution of helium-irradiated 6H–SiC subjected to different irradiation conditions and annealing temperatures: A multiple characterization study
Microstructural evolution of helium-irradiated 6H–SiC subjected to different irradiation conditions and annealing temperatures: A multiple characterization study
The microstructural phenomena occurring in 6H–SiC subjected to different irradiation conditions and annealing temperatures were investigated to assess the suitability of 6H–SiC as a structural material for nuclear applications. To this aim, a single crystal of 6H–SiC was subjected to He+ irradiation at 300 keV with different fluences and at temperatures ranging from 25 to 750 °C. Rutherford backscattering/channeling (RBS/C), X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses were combined to shed light on the microstructural changes induced by irradiation and subsequent annealing (750 to 1500 °C). At room temperature, amorphization starts to occur at a fluence of 2.5 × 1016 cm−2 (0.66 dpa). On the contrary, amorphization was prevented at high irradiation temperatures and fluences. Furthermore, a thin and highly strained region located around the maximum He concentration (Rp) formed. This region results from the accumulation of interstitial atoms which are driven toward the highly damaged region under the actions of a strain gradient and high temperature. Regardless of the fluence and irradiation temperature, the material stores elastic energy, which leads to the trapping of He in dissimilar defect geometries. For irradiation temperatures below 750 °C, helium was accumulated in bubbles which coarsened after annealing. On the other hand, for an irradiation temperature of 750 °C, helium was trapped in platelets (even for medium fluence), which evolved into a homogeneous dense array of cavities during annealing. DFT calculations show that the bubbles are under high pressure and contribute to developing the overall tensile strain in the single crystal 6H–SiC.
DFT, Platelets, Radiation damage, Strain distribution, Transmission electron microscopy
160-172
Daghbouj, N.
11efccbe-eb37-4f69-a8c4-1fd21889503e
Li, B. S.
ea2e7a47-e7eb-45b5-80ac-62566a975e24
Callisti, M.
86e03724-aacc-46d5-bccc-4c7025556667
Sen, H. S.
bb372413-c42d-4a9b-8337-bc27ee739f58
Karlik, M.
df29ecf1-6f1e-4713-a15a-82b321804596
Polcar, T.
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
December 2019
Daghbouj, N.
11efccbe-eb37-4f69-a8c4-1fd21889503e
Li, B. S.
ea2e7a47-e7eb-45b5-80ac-62566a975e24
Callisti, M.
86e03724-aacc-46d5-bccc-4c7025556667
Sen, H. S.
bb372413-c42d-4a9b-8337-bc27ee739f58
Karlik, M.
df29ecf1-6f1e-4713-a15a-82b321804596
Polcar, T.
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
Daghbouj, N., Li, B. S., Callisti, M., Sen, H. S., Karlik, M. and Polcar, T.
(2019)
Microstructural evolution of helium-irradiated 6H–SiC subjected to different irradiation conditions and annealing temperatures: A multiple characterization study.
Acta Materialia, 181, .
(doi:10.1016/j.actamat.2019.09.027).
Abstract
The microstructural phenomena occurring in 6H–SiC subjected to different irradiation conditions and annealing temperatures were investigated to assess the suitability of 6H–SiC as a structural material for nuclear applications. To this aim, a single crystal of 6H–SiC was subjected to He+ irradiation at 300 keV with different fluences and at temperatures ranging from 25 to 750 °C. Rutherford backscattering/channeling (RBS/C), X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses were combined to shed light on the microstructural changes induced by irradiation and subsequent annealing (750 to 1500 °C). At room temperature, amorphization starts to occur at a fluence of 2.5 × 1016 cm−2 (0.66 dpa). On the contrary, amorphization was prevented at high irradiation temperatures and fluences. Furthermore, a thin and highly strained region located around the maximum He concentration (Rp) formed. This region results from the accumulation of interstitial atoms which are driven toward the highly damaged region under the actions of a strain gradient and high temperature. Regardless of the fluence and irradiation temperature, the material stores elastic energy, which leads to the trapping of He in dissimilar defect geometries. For irradiation temperatures below 750 °C, helium was accumulated in bubbles which coarsened after annealing. On the other hand, for an irradiation temperature of 750 °C, helium was trapped in platelets (even for medium fluence), which evolved into a homogeneous dense array of cavities during annealing. DFT calculations show that the bubbles are under high pressure and contribute to developing the overall tensile strain in the single crystal 6H–SiC.
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Published date: December 2019
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Funding Information:
This study was financially supported by the Czech Science Foundation in the frame of the project 17-17921S , European Regional Development Fund (projects CZ.02.1.01/0.0/0.0/15_003/0000485 and CZ.02.1.01/0.0/0.0/16_019/0000778 ) and National Natural Science Foundation of China (Grant Nos. 11475229 and U1832133 ). Also, this work was supported by The Ministry of Education, Youth and Sports from the Large Infrastructures for Research, Experimental Development and Innovations project “IT4Innovations National Supercomputing Center – LM2015070”. M.C. acknowledges Innovate Uk (reference number: 113072 ) for financial support. The authors appreciate the laboratory of 320 keV high-voltage platform in the Institute of Modern Physics, CAS, for helium irradiation. We thank Prof. Alain Claverie for driving our attention to the loss of elastic energy resulting from amorphization and its effect on the shape and growth rate of precipitates.
Funding Information:
This study was financially supported by the Czech Science Foundation in the frame of the project 17-17921S, European Regional Development Fund (projects CZ.02.1.01/0.0/0.0/15_003/0000485 and CZ.02.1.01/0.0/0.0/16_019/0000778) and National Natural Science Foundation of China (Grant Nos. 11475229 and U1832133). Also, this work was supported by The Ministry of Education, Youth and Sports from the Large Infrastructures for Research, Experimental Development and Innovations project ?IT4Innovations National Supercomputing Center ? LM2015070?. M.C. acknowledges Innovate Uk (reference number: 113072) for financial support. The authors appreciate the laboratory of 320 keV high-voltage platform in the Institute of Modern Physics, CAS, for helium irradiation. We thank Prof. Alain Claverie for driving our attention to the loss of elastic energy resulting from amorphization and its effect on the shape and growth rate of precipitates.
Publisher Copyright:
© 2019 Acta Materialia Inc.
Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.
Keywords:
DFT, Platelets, Radiation damage, Strain distribution, Transmission electron microscopy
Identifiers
Local EPrints ID: 456221
URI: http://eprints.soton.ac.uk/id/eprint/456221
ISSN: 1359-6454
PURE UUID: a0d309ce-95ff-4903-bd6f-572640730df4
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Date deposited: 26 Apr 2022 18:33
Last modified: 18 Mar 2024 03:19
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Contributors
Author:
N. Daghbouj
Author:
B. S. Li
Author:
M. Callisti
Author:
H. S. Sen
Author:
M. Karlik
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