5-9 September 2016
Prague Congress Centre
Europe/Prague timezone

P1.178 Ion irradiation effects on microstructure and mechanical properties of VPS-W-coated F82H modified by FSP

5 Sep 2016, 14:20
1h 40m
Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Foyer 2A (2nd floor), 3A (3rd floor)

Prague Congress Centre

5. května 65, Prague, Czech Republic
Board: 178
Poster I. Materials Technology P1 Poster session

Speaker

Kazumi Ozawa (Fusion Research and Development Directorate)

Description

Reduced activation ferritic/martensitic steel, as typified by F82H, is a promising candidate for structural material of DEMO fusion reactors. To prevent plasma sputtering, tungsten (W) coating was essentially required. Vacuum plasma spray (VPS) is one of candidate coating processes, but the key issues are the degraded mechanical and thermal properties due to its relatively higher porosity and smaller density. Friction stir processing (FSP) was applied on VPS-W to solve the issues, and successively improved its hardness and thermal conductivity in unirradiated condition. Fine-grain microstructures induced by FSP would be a primary reason of this improvement. These structures were observed not only in VPS-W but also in F82H substrate, and it is expected that both VPS-W coating and substrate F82H could improve their irradiation-tolerance. This study aims to examine the irradiation effects on hardness and microstructure of VPS-W coated F82H modified by FSP, with a special emphasis on tolerance of void swelling in F82H substrate and W-F82H interface. F82H IEA-heat was used as a substrate in this study. 0.5 or 2 mm-thick W was coated on F82H by VPS and then modified with FSP. 6.4 MeV Fe3+3+ irradiation with 1.0 MeV He++ was conducted on W-F82H to ~50 dpa at 470°C at the DuET facility in Kyoto University. Nano-indentation tests were performed to evaluate hardness after the irradiation. Microstructure was characterized by OM, FE-SEM, and FE-TEM.  After dual ion irradiation to 20 dpa at 470°C, the void swelling of 0.48% was measured in F82H-IEA with the diameter of 5.19 nm and the number density of 4.18 × 102222 /m22. Contrarily, no void was detected in FSPed-F82H at the same condition.  From a microstructural point of view, it was suggested that lots of sinks introduced by plastic flow during FSP could decrease void swelling under the condition.

Co-authors

Hidetoshi Fujii (Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka, Japan) Hironori Kurotaki (Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori, Japan) Hiroyasu Tanigawa (Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori, Japan) Kazumi Ozawa (Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori, Japan) Masami Ando (Fusion Research and Development Directorate, Japan Atomic Energy Agency, Rokkasho, Aomori, Japan) Sosuke Kondo (Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto, Japan) Tatsuya Hinoki (Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto, Japan) Yoshiaki Morisada (Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka, Japan)

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