Experimental results simulating the effects of transmuted helium on the mechanical properties of SiC are presented. High-purity, stoichiometric chemically vapor-deposited SiC bend bars were cyclotron implanted using 37.7 MeV α particles at 590 °C. A uniform implantation to 100 and 1000 appm was carried out, with a maximum implantation depth of ≃0.46 mm. Samples were then neutron irradiated to a dose of ≃8 dpa at 800 °C, thereby simulating atomic displacements at dose rates and temperatures similar to those of a fusion blanket, while in the presence of high helium levels of (≃125 appm He/dpa). Results on as-implanted SiC yield statistically significant changes in bend strength, indent fracture toughness and density. It is clear that these changes are in part due to the ≃0.1 dpa dose coincident with the helium implantation. Following neutron irradiation a larger change in properties occurs, though the difference between the helium pre-injected SiC, and the irradiated control samples was not statistically significant.
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