24P080-P
Deuterium Retention in Advanced Tungsten Materials
先進タングステン系材料の水素同位体挙動
Makoto Oya1), Kazuhiro Uekita1), Yusuke Ohtsuka1), Yoshio Ueda1), Hiroaki Kurishita2)
大宅 諒1), 上北一博2)，大塚裕介1)，上田良夫1)，栗下裕明2)
1)

Graduate School of Engineering, Osaka University, Yamadaoka, Suita, Osaka565-0871, Japan
大阪大学 大学院工学研究科 〒565-0871 大阪府吹田市山田丘2-1
2)
Tohoku University Institute for Materials Research International Research Center for Nuclear Materials Science,Naritacho, Oaraimachi, Higashiibarakigun, Ibaraki311-1313, Japan
東北大学 金属材料研究所 〒311-1313 茨城県東茨城郡大洗町成田町2145-2
TFGR W (Toughened, Fine-Grained, Recrystallized W) specimens were exposed with a low energy (1keV) and high irradiation flux (1020 m-2s-1) of D ion beam at 200-400oC. The amounts of retained D ofTFGR W specimens were measured by thermal desorption spectroscopy (TDS) and the result wascompared with pure W specimens under the same experimental conditions. The retention amount of D in
TFGR W was higher than that of pure W.

1. Introduction
Tungsten (W) is a candidate of plasma-facing
materials in future fusion reactors and will be usedin divertor of the ITER. At present, a variety ofadvanced W materials with neutron irradiation
resistance have been developed, including TFGR W(Toughened, Fine-Grained Recrystallized W)
developed by Kurishita in Tohoku Univ. [1]. TFGR
W is the W material that has the average grain sizeof ~1μm with a small amount of TiC (~1wt%). The
fabrication procedure of TFGR W is shown in Ref.
[1]. This TFGR W has enhanced toughness
compared to other W materials. It is expected that
TFGR W will improve the poor irradiation
brittleness in W. However, TFGR W has limited
data on the applicability as wall-materials in theenvironment of the fusion reactor, especially forlow deuterium (D) retention. In this study, we show
the influences of the crystalline structure of W andthe addition of TiC into W to the behavior ofhydrogen isotopes in W.
2. Experiment
In this study, TFGR W-1.1wt%TiC samples of 10x 10 x 1 mm size were used. The D implantation
into TFGR W specimens was conducted withHigh-Flux ion beam Irradiation Test device (HiFIT)
in Osaka University [2], where the incident energy
is 1keV, and the flux density is ~1 x 1020 m-2s-1. The
TFGR W specimens were implanted to a fluence of1 x 1024 m-2 at irradiation temperatures of200-400oC. After the implantation, D retention inTFGR W specimens were measured by thermal
desorption spectroscopy (TDS). For comparison,
the experiments were also made with pure W
samples under the same conditions. The pure W
samples were fabricated by A.L.M.T Corp. andannealed at 1300oC in vacuum after mechanicalpolishing.
3. Results and Discussion
From the experimental results of previous studies,
there were fluence dependence and irradiation
temperature dependence of D retention in pure W.
D retention in pure W also changed with theincident irradiation energy and the annealing
temperature of W. We will investigate the trend of
D retention in pure W with respect to irradiation
temperature, fluence, incident energy and annealing
temperature.
D retention in TFGR W specimens was higher
than that of pure W specimens irradiated both at
200 oC and 400 oC. The D retention in pure W
decreased rapidly with temperature, while decreasein D retention in TFGR W is rather slowly. Thissuggests that TFGR W has trapping sites withhigher trapping energies than those in pure W. The
TFGR W specimens have C in form of TiC. Since
the chemical affinity is stronger between hydrogenisotopes and carbon than tungsten, D retention inTFGR W at elevated temperatures could be highcompared with pure W. More studies are necessaryto understand trapping mechanisms of TFGR W.
In this presentation, we will show the differencein D retention between pure W and TFGR W, anddiscuss the influence of irradiation temperature on
D retention.
Referance[1] H. Kurishita et al., J. Nucl. Mater. 398 (2010)87-92.
[2] Y. Ueda et al., Fusion Eng. Design 62 (2002)
255-261.