Positron Annihilation Study of Neutron-Irradiated Nuclear Reactor Pressure Vessel Steels and their Model Alloy: Effect of Purity on the Post-Irradiation Annealing Behavior

Abstract:

Post-irradiation annealing (PIA) behavior of irradiation-induced microstructural changes and hardening of two kind of A533B (first generation (1^stGENS: 0.16 wt.% Cu) and second generation (2^ndGENS: 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 1^stGENS, 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 2^ndGENS, 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.

• Periodical: Materials Science Forum (Volume 733)
• Pages: 257-263
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.733.257
• Online since: November 2012
• Authors: Akira Kuramoto, Yasuyoshi Nagai, T. Toyama, T. Takeuchi, M. Hasegawa
• Keywords: Atom Probe Tomography, Irradiation Hardening, Isochronal Annealing, Positron Annihilation, Reactor Pressure Vessel Steel, Solute Nano-Clusters, Vacancy-Related Defects

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