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Post-irradiation annealing (PIA) behavior of irradiation-induced microstructural changes and hardening of two kind of A533B (first generation (1stGENS: 0.16 wt.% Cu) and second generation (2ndGENS: 0.04 wt.% Cu)) steels after neutron-irradiation of 3.9 × 1019 n cm–2 at 290 °C has been studied by positron annihilation spectroscopy, atom probe tomography and Vickers microhardness measurements. In the 1stGENS, clear two recovery stages are observed: (i) as-irradiated state to 450 °C and (ii) 450 to 600 °C. The first stage is due to annealing out of the most of irradiation-induced vacancy-related defects (VRDs), and the second stage corresponds to dissolving irradiation-induced Cu-rich solute nano-clusters (CRSCs). The experimental hardening is almost twice of the hardening due to the CRSCs estimated by Russell-Brown model below 350 °C, but almost the same as the estimation from 400 to 550 °C. In the 2ndGENS, the VRDs and non-Cu-rich solute nano-clusters (NCRSCs) recover at 450 °C. No CRSC has been formed even in all the annealing process. The experimental hardening is almost twice of the hardening estimated due to the NCRSCs by Russell-Brown model below 400 °C.

Chemical reaction of SiO 2 and TZP(Tetragonal Zirconia Polycrystal) was directly observed by using TEM in-situ heating technique in order to understand the behavior of SiO 2 to TZP at high temperatures. The dynamic interaction of SiO 2 and TZP was recorded up to about 1400°C by the CCD camera-video system which was connected to TEM. It was found that most of SiO 2 phase is dissolved into ZrO 2 grains at above 1300°C. On the other hand, during cooling from the high temperature to around 400°C, amorphous SiO 2 reprecipitated from the surface of ZrO 2 grains and formed a thin layer around the ZrO 2 grains. This result agrees well with the fact that silicon segregates in the vicinity of the grain boundaries in SiO 2 -doped TZP. In order to confirm the grain boundary segregation at high temperatures, the grain boundaries in the quenched specimen were investigated by high resolution electron microscopy (HREM), energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). It was found that no amorphous phase was present between two adjacent grains even in the quenched samples. EDS analysis revealed that silicon segregated at the grain boundaries and its width was larger than that in as-sintered specimen. Electron energy loss near edge structure (ELNES) of O-Kedge was measured from both grain boundary and grain interior in the quenched specimen.

An interlaboratory comparison for positron annihilation lifetime (PAL) measurements for pure nickel and fused silica was performed. Based on the reported positron (for nickel) and positronium (for fused silica) lifetimes, the uncertainties in the PAL measurements were estimated.