309 中性子照射後の3Y-TZPセラミックスの超塑性変形特性(関東支部茨城講演会)

概要

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Applications of superplastic ceramics to high temperature gas-cooled reactor fields are very promising because of their excellent workability as well as high strength at elevated temperatures. Neutron irradiation effects on superplasticity of 3mol% yttria containing tetragonal zirconia polycrystals (3Y-TZP), a typical superplastic ceramic, were studied from the standpoint of their microstructure. Fast neutrons (>1MeV) were irradiated on the 3Y-TZP specimens to 2.5×10^<24> and 4.3×10<24> m^<-2> by JMTR at JAERI. Vickers hardness for the specimen was increased by the irradiation. It was shown that the flow stress of superplastic deformation was decreased by increasing the neutron fluence. The microstructures of the deformed specimens, observed by SEM, indicated that there are more big cavities at grain boundaries of the irradiated specimens than those of the un-irradiated ones. The morphology of the fracture surface of the specimen was also changed by the irradiation. It is most probable that the irradiation has weakened the grain boundary cohesion and irradiation-induced vacancy clusters would play an important role for it.
2005-09-08