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Suzudo, Tomoaki; Yamaguchi, Masatake; Hasegawa, Akira*
Journal of Nuclear Materials, 467(Part 1), p.418 - 423, 2015/12
Times Cited Count：45 Percentile：96.77(Materials Science, Multidisciplinary)Tungsten is expected to be a promising plasma-facing material for future fusion devices, but radiation-induced precipitation (RIP), which leads the material to hardening, is a concern at their practical use. One of the keys to accurate prediction of the emergence of RIP is migration of solute atoms, rhenium and osmium, that are produced by nuclear transmutation through irradiation. We conduct a series of numerical simulations using an atomic kinetic Monte Carlo method and investigate the migration of these solute atoms in the form of tungsten-rhenium and tungsten-osmium mixed dumbbells, considered to be the most efficient "carriers" of the solute atoms. We find that the low rotation energy barrier of these mixed dumbbells leading to three-dimensional migration greatly influences their diffusivities. The result also suggests that, although these dumbbells have three-dimensional motion, one cannot simply reduce their migration behavior to that of vacancy-like spherical objects.
Wakai, Eiichi; Hishinuma, Akimichi; Miwa, Yukio; Ouchi, Asao*; Isozaki, Seiichi*; Takaki, Seiichi*; Abiko, Kenji*
Materials Transactions, JIM, 41(1), p.136 - 140, 2000/01
no abstracts in English
Hamada, Shozo; *; *; Hishinuma, Akimichi; *; Koyama, Akira*
Journal of Nuclear Materials, 212-215, p.458 - 463, 1994/00
Times Cited Count：1 Percentile：17.88(Materials Science, Multidisciplinary)no abstracts in English
Shiraishi, K.
Nihon Genshiryoku Gakkai-Shi, 25(8), p.617 - 621, 1983/00
Times Cited Count：3 Percentile：44.36(Nuclear Science & Technology)no abstracts in English
Shiraishi, K.
Koon Gakkai-Shi, 6(5), p.179 - 186, 1980/00
no abstracts in English
Suzudo, Tomoaki; Hasegawa, Akira*
no journal, ,
Under neutron irradiation Re and Os are produced in W crystals, which are candidate materials for future fusion devices. These impurities are precipitated even under their solid solution limits, i.e. radiation induced precipitation (RIP) occurs. In the present study, we investigated the diffusions of Re and Os in W, which are essential to the development of the RIP. We found that Re and Os formed mixed dumbbells that rotate very easily, and that these dumbbells have 3D motions which are expected to suppress the cavity formation. This may be the explanation of the experimental fact that Re or Os inclusion in W crystals suppress the cavity formation.
Suzudo, Tomoaki; Hasegawa, Akira*
no journal, ,
Tungsten is expected to be a promising plasma-facing material for future fusion devices, but radiation-induced precipitation (RIP), which leads the material to hardening, is a concern at their practical use. One of the keys to accurate prediction of the emergence of RIP is migration of solute atoms, rhenium and osmium, that are produced by nuclear transmutation through irradiation. We conduct a series of numerical simulations using an atomic kinetic Monte Carlo method and investigate the migration of these solute atoms in the form of tungsten-rhenium and tungsten-osmium mixed dumbbells, considered to be the most efficient "carriers" of the solute atoms. We find that the low rotation energy barrier of these mixed dumbbells leading to three-dimensional migration greatly influences their diffusivities. The result also suggests that, although these dumbbells have three-dimensional motion, one cannot simply reduce their migration behavior to that of vacancy-like spherical objects.
Suzudo, Tomoaki; Tsuru, Tomohito; Hasegawa, Akira*
no journal, ,
Tungsten is expected to be a promising plasma-facing material for future fusion devices, but radiation-induced precipitation (RIP), which leads the material to hardening, is a concern at their practical use. One of the keys to accurate prediction of the emergence of RIP is stability and migration of solute atoms, rhenium (Re) and osmium (Os), that are produced by nuclear transmutation through irradiation. We conduct a series of numerical simulations using ab initio and an atomic kinetic Monte Carlo method to examine the behaviour of these solute elements. We find that tungsten interstitial atoms displaced by radiation favourably form mixed dumbbell with the solute atoms, and these mixed dumbbells have 3D motion instead of 1D motion of SIAs.
Suzudo, Tomoaki; Tsuru, Tomohito
no journal, ,
Rhenium (Re) and Osmium (Os) are produced from W through nuclear transmutation, and they would naturally be solute elements of W crystals under neutron irradiation. In such alloys, stable solvent-solute mixed dumbbells appear because the SIA and Re and Os substitutional atoms are attractive. Using the first-principles methods, we analyzed the atomistic migration patterns of these two transmuted elements and indicated that the mixed dumbbells composed of Re (or Os) and W atoms occasionally become separated, and the Re (or Os) atom jumps to the neighboring site forming another mixed dumbbell. Because the rotation of these mixed dumbbells is easy, these solute elements can be carried for long distance by iteration of jumping and rotation events.
