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Tsuru, Tomohito; Han, S.*; Matsuura, Shutaro*; Chen, Z.*; Kishida, Kyosuke; Lobzenko, I.; Rao, S.*; Woodward, C.*; George, E.*; Inui, Haruyuki*
Nature Communications (Internet), 15, p.1706_1 - 1706_10, 2024/02
Times Cited Count：0 Percentile：0(Multidisciplinary Sciences)Refractory high-entropy alloys (RHEAs) have attracted attention because of their potential for use in ultrahigh-temperature applications. Unfortunately, their body-centered-cubic (BCC) crystal structures make them more brittle than the ductile and fracture-resistant face-centered-cubic (FCC) HEAs. RHEAs also display significantly lower creep strengths than a leading Ni-base superalloy and its FCC matrix. To overcome these drawbacks and develop RHEAs into viable structural materials, improved fundamental understanding is needed of factors that control strength and ductility. Here we investigate two model RHEAs, TiZrHfNbTa and VNbMoTaW, and show that the former is plastically compressible down to 77 K, whereas the latter is not below 298 K. We find that hexagonal close-packed (HCP) elements in TiZrHfNbTa lower its dislocation core energy, increase its lattice distortion, and lower its shear modulus relative to VNbMoTaW whose elements are all BCC, leading to the formers higher ductility and modulus-normalized yield strength. Consistent with our yield strength models, primarily screw dislocations are present in TiZrHfNbTa after deformation, but equal numbers of edge and screw segments in VNbTaMoW. Dislocation cores are compact in VNbTaMoW and extended in TiZrHfNbTa, and different macroscopic slip planes are activated in the two RHEAs, which we attribute to the concentration of HCP elements. Our findings demonstrate how electronic structure changes related to the ratio of HCP to BCC elements can be used to control strength, ductility, and slip behavior to develop the next generation of high-temperature materials for more efficient power plants and transportation.
Mishima, Seiki*; Ogata, Sho*; Inui, Toru*; Yasuhara, Hideaki*; Kishida, Kiyoshi*; Aoyagi, Kazuhei
Dai-15-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), p.215 - 220, 2021/01
When the durability of the geological repository of high-level radioactive waste is evaluated, understanding the cracking behavior within the crystalline/sedimentary rocks during excavation of waste disposal cavities is important. In this study, we performed a numerical analysis that expressed the tunnel excavation carried out 350 m underground at the Horonobe Underground Research Center of the Japan Atomic Energy Agency. Simulated results are agreement with actual trends of fracture propagation, and the measured horizontal convergence of the tunnel was reproduced by the numerical analysis relatively well.
Ogata, Sho*; Yasuhara, Hideaki*; Aoyagi, Kazuhei; Kishida, Kiyoshi*
Proceedings of 53rd US Rock Mechanics/Geomechanics Symposium (USB Flash Drive), 6 Pages, 2019/06
Ishikawa, Tomohiro*; Yasuhara, Hideaki*; Sawada, Atsushi; Kishida, Kiyoshi*
Dai-50-Kai Jiban Kogaku Kenkyu Happyokai Rombunshu, p.515 - 516, 2015/06
no abstracts in English
Kishida, Kiyoshi*; Ishikawa, Tomohiro*; Higo, Yosuke*; Sawada, Atsushi; Yasuhara, Hideaki*
Proceedings of 49th US Rock Mechanics/Geomechanics Symposium (CD-ROM), 6 Pages, 2015/06
In order to estimate the changes in fracture aperture under various long-term confining and thermal conditions, measurements of the fracture aperture are conducted using microfocus X-ray CT. Through the imaging data, the altitude of the fracture surface and the contact points are evaluated, and contact ratios for the fracture, the JRC and the aperture distribution are estimated. On the other hand, measurements are also conducted using a laser scan profile sensor, and some parameters are estimated. In comparing these parameters, the validity of the X-ray CT data and an analysis of the data will be discussed. In addition, a fracture flow simulation will be conducted using the altitude and aperture data obtained by the microfocus X-ray CT.
Kishida, Keigo*; Kikuchi, Masahiro; Nakamura, Hideo*; Kobayashi, Yasuhiko; Ukai, Mitsuko*
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 90, 2015/03
Kishida, Keigo*; Kawamura, Shoei*; Kikuchi, Masahiro; Nakamura, Hideo*; Kobayashi, Yasuhiko; Ukai, Mitsuko*
JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 86, 2014/03
Kishida, Keigo*; Kawamura, Shoei*; Kameya, Hiromi*; Nakamura, Hideo*; Kikuchi, Masahiro; Kobayashi, Yasuhiko; Ukai, Mitsuko*
Radioisotopes, 63(3), p.131 - 137, 2014/03
Using Pulse-Electron Spin Resonance (Pulse-ESR) spectroscopy and Continuous Wave-Electron Spin Resonance (CW-ESR) spectroscopy, we revealed the relaxation time (T
, T
) of radicals induced in irradiated foods. The relaxation time was directly analyzed by Pulse-ESR. Using CW-ESR, the relaxation time was calculated by the measured spectrum parameter indirectly. We succeeded in the detection of Pulse-ESR signal of irradiated hard wheat flour and irradiated black pepper. It was suggested that using CW-ESR T and T can be calculated effectively, but the value was tend to slightly lower due to the parameters for calculation are affected by the contents of food especially protein.
Kawamura, Shoei*; Kishida, Keigo*; Kikuchi, Masahiro; Kobayashi, Yasuhiko; Ukai, Mitsuko*
Shokuhin Shosha, 48(1), p.3 - 10, 2013/09
no abstracts in English
Kishida, Keigo*; Kawamura, Shoei*; Nakamura, Hideo*; Kikuchi, Masahiro; Kobayashi, Yasuhiko; Ukai, Mitsuko*
Shokuhin Shosha, 48(1), p.11 - 18, 2013/09
no abstracts in English
Kishida, Kiyoshi*; Sawada, Atsushi; Yasuhara, Hideaki*; Hosoda, Takashi*
Soils and Foundations, 53(1), p.105 - 116, 2013/02
Times Cited Count：22 Percentile：63.11(Engineering, Geological)Considering the safe, long-term sequestration of energy byproducts, such as radioactive waste, one of the important parameters is the groundwater flow velocity through the void of rock masses and/or fractures. In this research work, two-dimensional seepage flow analyses, using the authors' proposed 2D model, with considering the inertia term, are carried out for single fracture permeability tests under conditions which allow for the application of the cubic law. In comparing the results of the experiments with the numerical simulations, the results of the simulation show a good agreement with the experimental results. From these simulation results, the fracture flow of an inhomogeneous structure is discussed, along with the local Reynolds number, and the resistance through the fracture geometry is considered. Consequently, under the condition of a mean Reynolds number of less than 1.0, the inertia terms cannot affect on the fracture flow, but the hydraulic resistance can affect.
Kawaguchi, Masanao; Kishi, Hirokazu*; Fujita, Tomoo; Kishida, Kiyoshi*
Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.337 - 342, 2013/01
For the selection of grout material for the construction of underground facilities for the geological disposal of High Level Waste, the criteria that is set by reference to IMA-project(which was a project of the grout material relating to the R20 program was conducted by POSIVA of Finland), has been used up to FY 2010. However, if the criteria of penetrability are fulfilled, the penetrability of the material for the candidate rock fracture is not ensured. Moreover, from the results of laboratory grout penetration test which has been carried out at FY 2010, it was appeared that the penetrability has been scarified in order to satisfy the strength and breeding characteristics. In this report, strength and bleeding properties are classified as reference properties, not as principal properties. Instead of that, new criteria of penetrability defined based on geological features at the site are proposed. Also the determination procedure of designed hydraulic fracture aperture which is one of above newly proposed criteria will be proposed.
Kaimori, Yoshihiko; Sakamoto, Yuki*; Kawamura, Shoei*; Kishida, Keigo*; Kikuchi, Masahiro; Nakamura, Hideo*; Kobayashi, Yasuhiko; Ukai, Mitsuko*
JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 79, 2013/01
no abstracts in English
Kishida, Keigo*; Kaimori, Yoshihiko*; Kawamura, Shoei*; Sakamoto, Yuki*; Nakamura, Hideo*; Kikuchi, Masahiro; Shimoyama, Yuhei; Kobayashi, Yasuhiko; Ukai, Mitsuko*
Shokuhin Shosha, 47(1), p.1 - 5, 2012/09
no abstracts in English
Tagawa, Masahito*; Kishida, Kazuhiro*; Yokota, Kumiko*; Matsumoto, Koji*; Yoshigoe, Akitaka; Teraoka, Yuden; Zhang, J.*; Minton, T. K.*
Protection of Materials and Structures from the Space Environment; Astrophysics and Space Science Proceedings, Vol.32, p.547 - 555, 2012/08
Kishida, Kiyoshi*; Kobayashi, Kenichiro*; Hosoda, Takashi*; Fujita, Tomoo; Kishi, Hirokazu; Kuzuha, Yuji; Nobuto, Jun*
Zairyo, 61(3), p.245 - 252, 2012/03
In this research work, the grout injection model of single fracture, in which non-Newtonian fluid and the inertia term are considered, has been developed. Then, the grout injection experiments of single fracture have been conducted and the numerical simulations have been also carried out. As compared our proposed model with past one, the remarkable difference in grout penetration could not be clearly observed. On the other hand, the difference in pressure at aperture entrance and penetration velocity of the grout could be clearly observed. Our proposed model could show the practical behavior against previous model. Moreover, it can be also confirmed that viscosity of grout material through the material experiments are differed with that through the parallel plate injection experiments.
Kishida, Kiyoshi*; Hosoda, Takashi*; Sawada, Atsushi; Sato, Hisashi; Nakashima, Shinichiro*; Yasuhara, Hideaki*
Harmonising Rock Engineering and the Environment, p.1327 - 1330, 2011/10
Although it is generally known that a natural rock fracture indicates a complex aperture distribution, the fracture is an ideal representation of the parallel plate model. The cubic law is applied to evaluate the hydraulic properties of fractured rock. From several previous research works, it is known that the cubic law can be applied when the Reynolds number is less than 1.0 and that the advection term can basically be ignored in such fracture flows. In this research work, two-dimensional seepage flow analyses, using the authors' proposed 2D model which is considered with the advection term, are carried out for single fracture hydro-conductivity experiments under conditions which allow for the application of the cubic law. From the numerical results, the validity of the 2D model is discussed along with the local Reynolds number and the application of the cubic law.
Kishida, Kiyoshi*; Kobayashi, Kenichiro*; Hosoda, Takashi*; Kuzuha, Yuji; Kishi, Hirokazu; Nobuto, Jun*
Doboku Gakkai Heisei-23-Nendo Zenkoku Taikai Dai-66-Kai Nenji Gakujutsu Koenkai Koen Gaiyoshu (DVD-ROM), p.81 - 82, 2011/09
no abstracts in English
Kishida, Kiyoshi*; Sawada, Atsushi; Sato, Hisashi; Onda, Shinichiro*; Hosoda, Takashi*
Dai-39-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM), p.287 - 292, 2010/01
no abstracts in English
irradiationFujisato, Toshiya*; Kikuchi, Masahiro; Sakashita, Tetsuya; Funayama, Tomoo; Kobayashi, Yasuhiko; Funamoto, Seiichi*; Kimura, Tsuyoshi*; Kishida, Akio*; Yamaoka, Tetsuji*
JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 119, 2008/03
Synthetic materials, such as ePTFE or Dacron are not suitable for reconstructing the small-diameter arteries. In contrast, tissue engineering (TE) graft has been attracting great attention recently. One of the promising approaches of TE grafts is using acellular tissues. The acellular scaffold may have the same structure and characteristics as the natural tissue and can be replaced with the host tissues. In this study, we prepared the acellular scaffold using irradiation, which is expected to induce the apoptosis of the cells.
