| 研究実績の概要 |
In this study, we investigated the inhomogeneous irradiation-induced hardening in structural materials for core components in nuclear applications. As the first step, in the FY2019, we developed the method to successfully correlate the irradiation-induced hardening to its corresponding crystal orientation, with the combined application of ion-accelerator irradiation, nano-indentation test, and electron backscattering diffraction analyses. The materials with strong texture in microstructure were utilized as experimental materials for this study, such as Zr-based alloys for fuel claddings in current light water reactors and oxide dispersion strengthened steel for next generation nuclear power reactors. In the case of Zr-Nb alloy, the obvious crystal orientation dependent irradiation-induced hardening is confirmed. The lowest hardening was observed at [0001] orientation, and the hardening gradually intensified towards prismatic orientations. Inhomogeneous irradiation-induced hardening was also exhibited in a textured 12Cr-ODS steel. The hardening was observed to be weaker in normal direction-transverse direction specimen relative to that of rolling direction-transverse direction irrespective of the dose of irradiation damage. Such anisotropic phenomena are presumed to be mainly attributed to the inhomogeneous grain structure with a very high grain aspect ratio in the employed steel.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
In the FY2019, the preparation of experimental materials was finished, and the methodology was successfully constructed. With the utilization of the developed method, inhomogeneous hardening behavior upon irradiation was confirmed in both Zr-Nb alloys and a 12Cr-ODS steel.
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| 今後の研究の推進方策 |
In the FY2020, following research activities are planned:
(1) to achieve a full-range crystal orientation dependent hardening in Zr-Nb alloy. It is because the current studies exhibited the data points dominantly located around c-axes due to the basal texture formed by the deformation.
(2) to perform detailed microstructure characterization in the low-indexed grains after nano-indentation testes. The thin foils will be prepared by focused ion beam technique, and transmission electron microscopy examination will be made to clarify the crystal-dependent deformation behaviors.
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