TY - JOUR
T1 - Microstructures of beta-silicon carbide after irradiation creep deformation at elevated temperatures
AU - Katoh, Yutai
AU - Kondo, Sosuke
AU - Snead, Lance L.
N1 - Funding Information:
The authors would like to thank Dr Y. Matsukawa for reviewing the manuscript. The irradiation program in this research was sponsored by the US Department of Energy Office of Nuclear Energy, Science and Technology, a Nuclear Energy Research Initiative (NERI) Project, under contract NEAF355 (AF3510) with UT-Battelle, LLC. The microstructural characterization and analysis were sponsored by the US Department of Energy Office of Fusion Energy Sciences under contract DE-AC05-00OR22725 with UT-Battelle, LLC,
PY - 2008/12/1
Y1 - 2008/12/1
N2 - Microstructures of silicon carbide were examined by transmission electron microscopy (TEM) after creep deformation under neutron irradiation. Thin strip specimens of polycrystalline and monocrystalline, chemically vapor-deposited, beta-phase silicon carbide were irradiated in the high flux isotope reactor to 0.7-4.2 dpa at nominal temperatures of 640-1080 °C in an elastically pre-strained bend stress relaxation configuration with the initial stress of ∼100 MPa. Irradiation creep caused permanent strains of 0.6 to 2.3 × 10-4. Tensile-loaded near-surface portions of the crept specimens were examined by TEM. The main microstructural features observed were dislocation loops in all samples, and appeared similar to those observed in samples irradiated in non-stressed conditions. Slight but statistically significant anisotropy in dislocation loop microstructure was observed in one irradiation condition, and accounted for at least a fraction of the creep strain derived from the stress relaxation. The estimated total volume of loops accounted for 10-45% of the estimated total swelling. The results imply that the early irradiation creep deformation of SiC observed in this work was driven by anisotropic evolutions of extrinsic dislocation loops and matrix defects with undetectable sizes.
AB - Microstructures of silicon carbide were examined by transmission electron microscopy (TEM) after creep deformation under neutron irradiation. Thin strip specimens of polycrystalline and monocrystalline, chemically vapor-deposited, beta-phase silicon carbide were irradiated in the high flux isotope reactor to 0.7-4.2 dpa at nominal temperatures of 640-1080 °C in an elastically pre-strained bend stress relaxation configuration with the initial stress of ∼100 MPa. Irradiation creep caused permanent strains of 0.6 to 2.3 × 10-4. Tensile-loaded near-surface portions of the crept specimens were examined by TEM. The main microstructural features observed were dislocation loops in all samples, and appeared similar to those observed in samples irradiated in non-stressed conditions. Slight but statistically significant anisotropy in dislocation loop microstructure was observed in one irradiation condition, and accounted for at least a fraction of the creep strain derived from the stress relaxation. The estimated total volume of loops accounted for 10-45% of the estimated total swelling. The results imply that the early irradiation creep deformation of SiC observed in this work was driven by anisotropic evolutions of extrinsic dislocation loops and matrix defects with undetectable sizes.
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U2 - 10.1016/j.jnucmat.2008.08.012
DO - 10.1016/j.jnucmat.2008.08.012
M3 - Article
AN - SCOPUS:55949124149
VL - 382
SP - 170
EP - 175
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
SN - 0022-3115
IS - 2-3
ER -