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Title: Swelling of SiC at Intermediate and High Irradiation Temperatures

Authors:
 [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
966067
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Nuclear Materials; Journal Volume: 367; Journal Issue: 1
Country of Publication:
United States
Language:
English

Citation Formats

Snead, Lance Lewis, Katoh, Yutai, and Connery, Scott D. Swelling of SiC at Intermediate and High Irradiation Temperatures. United States: N. p., 2007. Web. doi:10.1016/j.jnucmat.2007.03.097.
Snead, Lance Lewis, Katoh, Yutai, & Connery, Scott D. Swelling of SiC at Intermediate and High Irradiation Temperatures. United States. doi:10.1016/j.jnucmat.2007.03.097.
Snead, Lance Lewis, Katoh, Yutai, and Connery, Scott D. Mon . "Swelling of SiC at Intermediate and High Irradiation Temperatures". United States. doi:10.1016/j.jnucmat.2007.03.097.
@article{osti_966067,
title = {Swelling of SiC at Intermediate and High Irradiation Temperatures},
author = {Snead, Lance Lewis and Katoh, Yutai and Connery, Scott D},
abstractNote = {},
doi = {10.1016/j.jnucmat.2007.03.097},
journal = {Journal of Nuclear Materials},
number = 1,
volume = 367,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • We present experimental data that characterize the behavior of various grades of beryllium subjected to high integrated neutron fluxes and high irradiation temperatures. Post-irradiation densities and structures of samples were determined. In analyzing the results, it can be concluded that, during high- temperature irradiation, the density of beryllium decreases, the decrease in density being proportional to the integrated neutron flux and the irradiation temperature. Moreover, the change in density depends significantly on the kind of material. For mono- and bicrystal beryllium it is less than for cermet beryllium; the swelling of the latter, in turn, increases with size of initialmore » particles. Results of structural studies indicate that the change in cermet beryllium density is to a great extent determined by the rate of coalescence of pores in boundary regions, and that coalescence increases with size of grains. Finally, the results present a picture of density change dose dependence in hot-pressed beryllium for the temperature range of practical interest (600 to 700 deg C).« less
  • Previously, results for CVD-SiC joints created using solid state displacement reactions to form a dual-phase SiC/MAX phase irradiated at 800°C and 5 dpa indicated some extent of cracking in the joint and along the CVD-SiC/joint interface. This paper elucidates the origin of cracking by thermomechanical modeling combined with irradiation-induced swelling effects using a continuum damage approach with support of micromechanical modeling. Three irradiation temperatures (400°C, 500°C and 800°C) are considered assuming experimental irradiation doses in a range leading to saturation swelling in SiC. The analyses indicate that a SiC/MAX joint heated to 400°C fails during irradiation-induced swelling at this temperaturemore » while it experiences some damage after being heated to 500°C and irradiated at the same temperature. However, it fails during cooling from 500°C to room temperature. The joint experiences minor damage when heated to and irradiated at 800°C but does not fail after cooling. The prediction agrees with the experimental findings available for this case.« less
  • The microstructural evolution of SiC/SiC composites after Si{sup 2+} with/without He{sup +} ion irradiation was studied using transmission electron microscopy. The temperature, displacement damage level, and He/dpa ratio were 1273/1673K, 10/100dpa and 0/60appmHe/dpa, respectively. In 10dpa single-ion irradiation, no cavity was detected at 1273 and 1673K. But cavities were observed locally at 1673K, 100dpa. In dual-ion irradiation, cavities were observed at 1673K, 100dpa. Helium bubbles (d<5nm) were formed densely on {l_brace}111{r_brace} faulted planes in the fiber and matrix. And lens-shaped cavities (major axis 2a=20-50nm) were formed on grain boundaries in the matrix. The swelling by cavities in CVI matrix ismore » about 0.5% at 80dpa and 0.7% at 130dpa. Loss of PyC layer beneath the irradiated surface was observed (single-ion: about 500nm, dual-ion: about 1 {mu}m). And the thickness of the PyC layer expands after single/dual-ion irradiation (single-ion: 12%, dual-ion: 29% increase). But Tyranno-SA/PyC/CVI composites shows showed better microstructural stability than expected at 1673K.« less
  • Previously, results for CVD-SiC joined by a solid state displacement reaction to form a dual-phase SiC/MAX phase joint subsequently irradiated at 800 °C to 5 dpa indicated some cracking in the joint. Here, this paper elucidates the cracking origin by developing a model that accounts for differential thermal expansion and irradiation-induced swelling between the substrate and joint materials by using a continuum damage mechanics approach with support from micromechanical modeling. Damage accumulation in joined specimens irradiated at four temperatures (300 °C, 400 °C, 500 °C and 800 °C) is analyzed. We assume the experimental irradiation dose is sufficient to causemore » saturation swelling in SiC. The analyses indicate that the SiC/MAX joint survives irradiation-induced swelling at all the irradiation temperatures considered. The joint experiences only minor damage when heated to and irradiated at 800 °C as well as cooling to room temperature. The prediction agrees with the experimental findings available for this case. However, the joint heated to 300 °C suffers severe damage during irradiation-induced swelling at this temperature, and additional damage after cooling to room temperature. Irradiation at 400 °C and subsequent cooling to room temperature produced similar damage to the irradiation 300 °C case, but to a lesser extent. Finally, the joint heated to 500 °C and irradiated at this temperature suffered only very minor damage, but further moderate damage occurred after cooling to room temperature.« less