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若井 栄一; 能登 裕之*; 牧村 俊助*; 石田 卓*; 古谷 一幸*; 柴山 環樹*
no journal, ,
近年、高エントロピー合金は、その原子混合比や組成から、従来材料よりも高強度で延性に優れることから、世界中の研究機関で精力的に研究開発が進められている。本研究では、チタン基高エントロピー合金(HEA)であるTiVCrZrTa、TiVZrTaAl、TiVCrZrWをコールドクルーシブル浮上溶解法により溶解し、1200
Cで5時間、均質化熱処理を施した。これらのHEAの機械的特性試験と特性を調査した。TiVCrZrTa系のHEAは、他のチタン基のHEAに比べて、比較的に良好な熱間圧延性と熱間鍛造性を有することが分かった。また、これらのチタン基HEAのビッカース硬さは、通常のチタン合金よりもかなり高い値を持つことが分かった。
齋藤 隼輝*; Yu, H.*; 井上 耕治*; Zimo, G.*; 近藤 創介*; 永井 康介*; 大場 洋次郎; 廣井 孝介; 笠田 竜太*
no journal, ,
Oxide-dispersion-strengthened copper alloys (ODS-Cu) have excellent high strength and thermal conductivity and thus are promising materials for divertor heat sink in future fusion reactors. Zr addtion is effective for the improvement of mechanical and irradiation properties because Zr gives the refinement and densification of the oxide particles. Nanostructural observation using small-angle X-ray scattering, three-dimensional atom probe tomography, and transmission electron microscope provide that Zr forms yttria-stabilized zirconia (YSZ). This can be related to the refinement of the oxide particles.
谷川 博康*; 中島 基樹*; 酒瀬川 英雄; 安堂 正己*; 渡辺 淑之*; 野澤 貴史*; 加藤 雄大*; 中田 隼矢*
no journal, ,
Reduced activation ferritic/martensitic (RAFM) steels have been developed as the candidate structural material of fusion reactor breeding blanket system, since fast reactor (FBR) irradiation experiments on commercial heat-resistant ferritic steels, which showed high swelling resistance, opened up the possibility of their application in fusion reactors. Phase stability, which is the key to creep properties in heat-resistant ferritic steels by preventing dislocation glide, was considered to be a key property for achieving high defect absorption strength, which is the key to irradiation resistance. One of RAFM steels intensively developed in Japan is F82H (Fe-8Cr-2W-0.2V-0.04
0.10Ta-0.1C). The 5-ton F82H melted in 1994 and 1995, together with their welded materials, were subjected to round-robin tests under the international cooperation of the International Energy Agency (IEA). As a part of IEA collaboration, the creep test campaign for these F82H IEA heat was initiated around 1997, and the world's longest creep test on RAFM steel, over 20 years, was completed with creep fracture times of 176019.5 hours (20.1 years) at 226 MPa/500 degree Celsius and 213475.0 hours (24.4 years) at 26.5 MPa /650 degree Celsius. In this study, detailed microstructure analyses concerning phase stability, especially the stability of precipitates, were carried out on the gage and grip section of fractured specimens of F82H after long-term creep testing. The phase stability of crept F82H was compared with that observed in aged and irradiated F82H, and the correlation between the two was discussed.