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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.48  No.9 (2007)  >  pp.2399-2402

MATERIALS TRANSACTIONS
<<Previous article Vol.48  No.9 (2007)   pp.2399 - 2402 Next article>>

Effects of Transmutation Elements on Neutron Irradiation Hardening of Tungsten

Takashi Tanno1), Akira Hasegawa1), Jian-Chao He1), Mitsuhiro Fujiwara1), Shuhei Nogami1), Manabu Satou1), Toetsu Shishido2) and Katsunori Abe1)
1) Department of Quantum Science and Energy Engineering, Faculty of Engineering, Tohoku University
2) Institute for Materials Research, Tohoku University


Tungsten (W) is a candidate material for Plasma facing materials of fusion reactors. During fusion reactor operation, not only irradiation damages but also transmutation elements such as rhenium (Re) and osmium (Os) are produced by neutron irradiation. As a result, the original pure tungsten changes to W-Re or W-Re-Os alloys. Thus, the mechanical and physical properties are expected to change. The aim of this study is to investigate the effects of transmutation elements on neutron irradiation hardening and microstructure changes of tungsten.
To simulate the effects of transmutation elements, tungsten base model alloys were used in this study. The examined compositions of the alloys were selected from the calculated changes in solid solution area of W-Re-Os alloy. Neutron irradiation was performed in fast test reactor JOYO in JAEA. The irradiation damages and temperature ranges were 0.17–1.54 dpa and 400–750°C respectively. After the irradiation, Vickers hardness test and TEM observation were performed.
There were clear differences between Re and Os in effects on irradiation hardening. In the case of W-Re alloys, when damages were less than 0.40 dpa, the irradiation hardenings were nearly equal to those of pure tungsten independent of Re addition. But when the damage was 1.54 dpa, the irradiation hardenings increased lineally with Re content. Microstructural observations showed that precipitations mainly formed in W-Re alloys. In the case of W-Os alloys, the irradiation hardenings (ΔHv) of W-3Os alloys were larger than those of pure tungsten. And the differences were about 400 independent of dpa and irradiation temperature. Effects of Re and Os on irradiation hardening based on the microstructural observations were discussed.


Keyword:
tungsten, solid transmutation elements, neutron irradiation hardening, precipitation, void lattice

Received: April 24, 2007
Accepted: June 29, 2007 , Published online: August 25, 2007
Copyright (c) 2007 The Japan Institute of Metals

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