Dislocation core structure and motion in pure titanium and titanium alloys; A First-principles study

Tsuru, Tomohito; Itakura, Mitsuhiro; Yamaguchi, Masatake; Watanabe, Chihiro*; Miura, Hiromi*

Computational Materials Science, 203, p.111081_1 - 111081_9, 2022/02

https://doi.org/10.1016/j.commatsci.2021.111081

The deformation mode of some titanium (Ti) alloys differs from that of pure Ti due to the presence of alloying elements in -phase. Herein, we investigated all possible slip modes in pure Ti and the effects of Al and V solutes as typical additive elements on the dislocation motion in -Ti alloys using density functional theory (DFT) calculations. The stacking fault (SF) energies in possible slip planes indicated that both Al and V solutes reduce the SF energy in the basal plane and, in contrast, the Al solute increases the SF energy particularly in the prismatic plane. DFT calculations were subsequently performed to simulate dislocation core structures. The energy landscape of the transition between all possible dislocation core structures and the barriers for dislocation glide in various slip planes clarified the nature of dislocation motion in pure Ti. (i) the energy of prismatic core is higher than most stable pyramidal core, and thereby dislocations need to overcome the energy barrier of the cross-slip (22.8 meV/b) when they move in the prismatic plane, (ii) the energy difference between the prismatic and basal cores is larger (127 meV/b), that indicates the basal slip does not activate, (iii) however, the Peierls barrier for motion in the basal plane is not as high (16 meV/b). Direct calculations for the dislocation core around solutes revealed that both Al and V solutes facilitate dislocation motion in the basal plane by reducing the energy difference between the prismatic and basal cores. The effect of solutes characterizes the difference in the deformation mode of pure Ti and -Ti alloys.

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.

Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01

https://doi.org/10.7566/JPSJ.87.014201

Excitation functions of quasielastic scattering cross sections for the Ca + Pb, Ti + Pb, and Ca + Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the Ca + Pb and Ti + Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the Ca + Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.

Contrast variation by dynamic nuclear polarization and time-of-flight small-angle neutron scattering, 1; Application to industrial multi-component nanocomposites

Noda, Yohei*; Koizumi, Satoshi*; Masui, Tomomi*; Mashita, Ryo*; Kishimoto, Hiromichi*; Yamaguchi, Daisuke; Kumada, Takayuki; Takata, Shinichi; Oishi, Kazuki*; Suzuki, Junichi*

Journal of Applied Crystallography, 49(6), p.2036 - 2045, 2016/12

https://doi.org/10.1107/S1600576716016472

Development of multi-purpose MW gyrotrons for fusion devices

Minami, Ryutaro*; Kariya, Tsuyoshi*; Imai, Tsuyoshi*; Numakura, Tomoharu*; Endo, Yoichi*; Nakabayashi, Hidetaka*; Eguchi, Taku*; Shimozuma, Takashi*; Kubo, Shin*; Yoshimura, Yasuo*; et al.

Nuclear Fusion, 53(6), p.063003_1 - 063003_7, 2013/06

https://doi.org/10.1088/0029-5515/53/6/063003

Development of proposed guideline of flow-induced vibration evaluation for hot-leg piping in a sodium-cooled fast reactor

Sakai, Takaaki; Yamano, Hidemasa; Tanaka, Masaaki; Ono, Ayako; Ohshima, Hiroyuki; Kaneko, Tetsuya*; Hirota, Kazuo*; Sago, Hiromi*; Xu, Y.*; Iwamoto, Yukiharu*; et al.

Proceedings of 15th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-15) (USB Flash Drive), 13 Pages, 2013/05

The development of flow-induced vibration evaluation methodology has reached a milestone that separate-effect experimental data under a high Reynolds number regime including swirl and deflected inflow conditions are available for the validation of the methodology. On the other hand, technical standards are desirable to be documented for designers of sodium-cooled fast reactors. From such a background, the documentation of a flow-induced vibration design guideline has been made for the hot-leg piping of Japan sodium-cooled fast reactor. This paper describes the design guideline of the flow-induced vibration evaluation methodology, which has been informed from main separate-effect experiments, as well as supplemental interpretation for the guideline.

Production and decay properties of Hs and Hs

Sato, Nozomi; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Kaji, Daiya*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozeki, Kazutaka*; Sumita, Takayuki*; Yoneda, Akira*; et al.

Journal of the Physical Society of Japan, 80(9), p.094201_1 - 094201_7, 2011/09

https://doi.org/10.1143/JPSJ.80.094201

Decay properties of Hs and Hs produced in the Pb(Fe, ) [=1, 2] reactions were studied using a gas-filled recoil ion separator at the linear accelerator facility of RIKEN. A total of 6 decay chains were assigned to Hs. Cross sections for the Hs production in the Pb(Fe,) and Pb(Fe,) reactions were measured to be pb and pb, respectively. The isotope Hs decayed with a half-life of ms by -particle emission and spontaneous fission. The -particle energy of Hs was observed at 10.610.04 and 10.800.08 MeV. The spontaneous fission branch of Hs was found to be .

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in and Au+Au collisions at = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

https://doi.org/10.1103/PhysRevC.83.044912

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.

Decay properties of Bh and Db produced in the Cm + Na reaction

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi*; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

Journal of the Physical Society of Japan, 78(6), p.064201_1 - 064201_6, 2009/06

https://doi.org/10.1143/JPSJ.78.064201

Decay properties of an isotope Bh and its daughter nucleus Db produced by the Cm(Na,5) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. Bh was clearly identified from the correlation of the known nuclide, Db. The obtained decay properties of Bh and Db are consistent with those observed in the 113 chain, which provided further confirmation of the discovery of 113.

Production of a new hassium isotope Hs

Kaji, Daiya*; Morimoto, Koji*; Sato, Nozomi*; Ichikawa, Takatoshi*; Ideguchi, Eiji*; Ozeki, Kazutaka*; Haba, Hiromitsu*; Koura, Hiroyuki; Kudo, Yuki*; Ozawa, Akira*; et al.

Journal of the Physical Society of Japan, 78(3), p.035003_1 - 035003_2, 2009/03

https://doi.org/10.1143/JPSJ.78.035003

A new hassium isotopes Hs is directly produced for the first time. The experiment was performed at the linear accelerator (RILAC) facility in RIKEN (the Institute of Physical and Chemical Research) from Jun. 19 to 25. In the 25-h irradiation of Fe on Pb and 46-h irradiation of Fe on Pb, 8 decay chains and 1 decay chain, respectively, were observed. All decay chains were assigned to subsequent decays from Hs. The half-life of Hs is 0.60 ms. In this experiment, the total beam dose was ions for Fe and ions for Fe. The production cross section corresponding to 8 decay events and 1 decay chain was deduced to be 21 pb and 1.6 pb by assuming that the transmission of the system is 80%.

Development of the volume reduction treatment of solid waste system by ultra-high frequency induction furnace

Sakakibara, Tetsuro; Aoyama, Yoshio; Yamaguchi, Hiromi; Sasaki, Naoto*; Nishikawa, Takeshi*; Murata, Minoru*; Park, J.*; Taniguchi, Shoji*; Fujita, Michiru*; Fukuda, Tomoyuki*; et al.

Proceedings of International Waste Management Symposium 2009 (WM '09) (CD-ROM), 15 Pages, 2009/03

http://www.wmsym.org/archives/2009/pdfs/9356.pdf

The volume reduction treatment of solid waste system by ultra-high frequency induction furnace (UHFIF) was developed from FY2005 to FY2007. Basic data for melting performance were collected by non-radioactive experiments using the bench scale UHFIF with a crucible capacity of 10 liters. Based on the obtained data, engineering specifications were evaluated for a demonstration scale UHFIF with a crucible capacity of 30 liters. A new demonstration scale UHFIF was constructed and melting experiments of surrogate wastes were carried out by this furnace. It was confirmed that the demonstration scale UHFIF can melt ferrous metal, ceramics and aluminum all together and stabilize aluminum by oxidation to alumina. Density, chemical composition, and surface condition of the solidified substances were analyzed, and homogeneity of the solidified substances was confirmed. Melting behavior in the demonstration scale UHFIF was analyzed by computer simulation and simulation results agreed well with the experimental ones. From the design study for a full scale UHFIF with a crucible capacity of 100 liters, basic specifications were evaluated for the full scale UHFIF. Based on the obtained specification, melting behavior in the full scale UHFIF was analyzed by computer simulation.