Abstract
The purpose of this investigation is to experimentally quantify the stored energy release upon thermal annealing of previously irradiated high-purity silicon carbide (SiC.) Samples of highly-faulted polycrystalline CVD β-SiC and single crystal 6H–SiC were irradiated in a mixed spectrum fission reactor near 60 °C in a fluence range from 5 × 1023 to 2 × 1026 n/m2 (E > 0.1 MeV), or about 0.05–20 dpa, in order to quantify the stored energy release and correlate the release to the observed microscopic swelling, lattice dilation, and microstructure as observed through TEM. Within the fluence of this study the crystalline material was observed to swell to a remarkable extent, achieving 8.13% dilation, and then cross a threshold dose for amorphization at approximately 1 × 1025 n/m2 (E > 0.1 MeV) Once amorphized the material attains an as-amorphized swelling of 11.7% at this irradiation condition. Coincident with the extraordinary swelling obtained for the crystalline SiC, an equally impressive stored energy release of greater than 2500 J/g at the critical threshold for amorphization is inferred. As expected, following amorphization the stored energy in the structure diminishes, measured to be approximately 590 J/g. Generally, the findings of stored energy are consistent with existing theory, though the amount of stored energy given the large observed crystalline strain is remarkable. The overall conclusion of this work finds comparable stored energy in SiC to that of nuclear graphite, and similar to graphite, a stored energy release in excess of its specific heat in some irradiation conditions.
Original language | English |
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Pages (from-to) | 181-188 |
Number of pages | 8 |
Journal | Journal of Nuclear Materials |
Volume | 514 |
DOIs | |
State | Published - Feb 2019 |
Funding
This work was supported by the U.S. Department of Energy , Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-051D14517 as part of a Nuclear Science User Facility experiment. The authors would like to thank the NSUF office for enabling this research as well as the members of the Low Activation Materials Development Laboratory (LAMDA) at ORNL and in particular Wallace Porter for their experimental support. The Principal Investigator was supported through a Department of Energy Office of Fusion Energy Sciences , Project Number 79446 .
Funders | Funder number |
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Department of Energy Office of Fusion Energy Sciences | 79446 |
U.S. Department of Energy | DE-AC07-051D14517 |
Office of Nuclear Energy |