Evaluation of defect formation in helium irradiated Y2O3 doped W-Ti alloys by positron annihilation and nanoindentation

JOURNAL OF NUCLEAR MATERIALS

卷:494

Article

Richter, Asta¹  Anwand, Wolfgang²  Chen, Chun-Liang³  Boettger, Roman⁴ 

[1] Tech Univ Appl Sci Wildau, Dept Engn Phys, Hsch Ring 1, D-15745 Wildau, Germany

[2] Helmholtz Zentrum Dresden Rossendorf, Inst Radiat Phys, Bautzner Landstr 400, D-01328 Dresden, Germany

[3] Natl Dong Hwa Univ, Dept Mat Sci & Engn, Hualien 97401, Taiwan

[4] Helmholtz Zentrum Dresden Rossendorf, Inst Ion Beam Phys & Mat Res, Bautzner Landstr 400, D-01328 Dresden, Germany

关键词: W-Ti-ODS alloys;    He implantation;    Positron annihilation spectroscopy;    Nanoindentation;    Vacancy defects;   

DOI  :  10.1016/j.jnucmat.2017.07.039

来源: Elsevier

【 摘 要 】

Helium implanted tungsten-titanium ODS alloys are investigated using positron annihilation spectroscopy and nanoindentation. Titanium reduces the brittleness of the tungsten alloy, which is manufactured by mechanical alloying. The addition of Y2O3 nanoparticles increases the mechanical properties at elevated temperature and enhances irradiation resistance. Helium ion implantation was applied to simulate irradiation effects on these materials. The irradiation was performed using a 500 kV He ion implanter at fluences around 5 x 10(15) cm(-2) for a series of samples both at room temperature and at 600 degrees C. The microstructure and mechanical properties of the pristine and irradiated W-Ti-ODS alloy are compared with respect to the titanium and Y2O3 content. Radiation damage is studied by positron annihilation spectroscopy analyzing the lifetime and the Doppler broadening. Three types of helium-vacancy defects were detected after helium irradiation in the W-Ti-ODS alloy: small defects with high helium-to-vacancy ratio (low S parameter) for room temperature irradiation, larger open volume defects with low helium-to-vacancy ratio (high S parameter) at the surface and He-vacancy complexes pinned at nanoparticles deeper in the material for implantation at 600 degrees C. Defect induced hardness was studied by nanoindentation. A drastic hardness increase is observed after He ion irradiation both for room temperature and elevated irradiation temperature of 600 degrees C. The Ti alloyed tungsten-ODS is more affected by the hardness increase after irradiation compared to the pure W-ODS alloy. (C) 2017 Elsevier B.V. All rights reserved.

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