Yoneda, Yasuhiro; Harada, Makoto; Takano, Masahide
Transactions of the Materials Research Society of Japan, 44(2), p.61 - 64, 2019/04
We performed three-dimensional observation of simulated fuel debris using Synchrotron Computed Tomography (CT). CT was used to make the inside of fuel debris clear. The CT observation provides that a clear contrast in the zirconia rich part and concrete rich part. Zirconia heavier than concrete moved to the lower part when crystals precipitate and aggregates near the bottom surface. As a result, phase separation occurs. The phase separation is caused by the difference in the composition ratio of zirconia, and can also be observed difference in crystal growth mode by composition ratio.
Sato, Yuji*; Tsukamoto, Masahiro*; Shobu, Takahisa; Yamashita, Yoshihiro*; Yamagata, Shuto*; Nishi, Takaya*; Higashino, Ritsuko*; Okubo, Tomomasa*; Nakano, Hitoshi*; Abe, Nobuyuki*
Applied Physics A, 124(4), p.288_1 - 288_6, 2018/04
The dynamics of titanium (Ti) melted by laser irradiation was investigated in a synchrotron radiation experiment. As an indicator of wettability, the contact angle between a selective laser melting (SLM) baseplate and the molten Ti was measured by synchrotron X-rays at 30 keV during laser irradiation. As the baseplate temperature increased, the contact angle decreased, down to 28 degrees at a baseplate temperature of 500C. Based on this result, the influence of wettability of a Ti plate fabricated by SLM in a vacuum was investigated. It was revealed that the improvement of wettability by preheating suppressed sputtering generation, and a surface having a small surface roughness was fabricated by SLM in a vacuum.
Toyokawa, Hidenori*; Saji, Choji*; Kawase, Morihiro*; Wu, S.*; Hurukawa, Yukihito*; Kajiwara, Kentaro*; Sato, Masugu*; Hirono, Toko*; Shiro, Ayumi*; Shobu, Takahisa; et al.
Journal of Instrumentation (Internet), 12(1), p.C01044_1 - C01044_7, 2017/01
We have been developing CdTe pixel detectors combined with a Schottky diode sensor and photon-counting ASICs. The hybrid pixel detector was designed with a pixel size of 200 micro-meter by 200 micro-meter and an area of 19 mm by 20 mm or 38.2 mm by 40.2 mm. The photon-counting ASIC, SP8-04F10K, has a preamplifier, a shaper, 3-level window-type discriminators and a 24-bits counter in each pixel. The single-chip detector with 100 by 95 pixels successfully operated with a photon-counting mode selecting X-ray energy with the window comparator and stable operation was realized at 20C. We have performed a feasibility study for a white X-ray microbeam experiment. Laue diffraction patterns were measured during the scan of the irradiated position in a silicon steel sample. The grain boundaries were identified by using the differentials between adjacent images at each position.
Sano, Mutsumi*; Takahashi, Sunao*; Watanabe, Atsuo*; Shiro, Ayumi*; Shobu, Takahisa
Materials Research Proceedings, Vol.2, p.609 - 614, 2017/00
Dislocation densities of GlidCop with compressive strain applied at high temperature were examined by X-ray line profile analyses with synchrotron radiation. In order to evaluate the dislocation density, we applied the modified Williamson-Hall and modified Warren-Averbach method. The dislocation densities of GlidCop with compressive strain from 0.011-0.04 were in the range of 5.7-8.010m.
Shimizu, Kenichi*; Koike, Yuki*; Yamada, Taiki*; Oharada, Kazuya*; Tanaka, Keisuke*; Shobu, Takahisa
Zairyo, 65(9), p.657 - 664, 2016/09
The internal stress in crystalline thermoplastics, polyphenylene sulphide (PPS), reinforced by carbon fibers of 30 mass% was measured by the diffraction method using synchrotron with energy of 12.3 keV. The stress in the matrix was determined by the sin2psi method with side-inclination optics of transmitted X-ray diffractions. Using skin-layer strips cut parallel, perpendicular and 45 degree to the molding direction of the injection molded plates, the matrix stress was measured under the uniaxial applied stress. The experimental values were at least qualitatively agreed with the prediction derived based on micromechanics. The quantitative difference between experiment and prediction is mainly due to the neglect of the distribution of fiber orientations in the micromechanics prediction. These residual stresses were caused by the mismatch of the thermal expansion coefficient between matrix and fibers.
Liss, K.-D.*; Funakoshi, Kenichi*; Dippenaar, R. J.*; Higo, Yuji*; Shiro, Ayumi*; Reid, M.*; Suzuki, Hiroshi; Shobu, Takahisa; Akita, Koichi
Metals, 6(7), p.165_1 - 165_22, 2016/07
Titanium aluminides find application in modern light-weight, high-temperature turbines, such as aircraft engines, but suffer from poor plasticity during manufacturing and processing. Huge forging presses enable materials processing in the 10 GPa range and hence, it is necessary to investigate the phase-diagrams of candidate materials under these extreme conditions. Here we report on an in-situ synchrotron X-ray diffraction study in a large-volume-press of a modern ( + ) two-phase material, Ti-45Al-7.5Nb-0.25C, under pressures up to 9.6 GPa and temperatures up to 1686 K. At room temperature, the volume response to pressure is accommodated by the transformation rather than volumetric strain, expressed by apparently high bulk moduli of both constituent phases. Crystallographic aspects, specifically lattice strain and atomic order are discussed in detail. It is interesting to note that this transformation takes place despite an increase in atomic volume, which is due to the high ordering energy of . Upon heating under high pressure, both the eutectoid and -solvus transition temperatures are elevated, and a third, cubic -phase is stabilized above 1350 K. Earlier research has shown that this -phase is very ductile during plastic deformation, essential in near-conventional forging processes. Here, we were able to identify an ideal processing window for near-conventional forging, while the presence of the detrimental -phase is not present under operating conditions. Novel processing routes can be defined from these findings.
Nakatani, Hayato*; Kajiwara, Kentaro*; Akita, Koichi; Ogihara, Shinji*
Proceedings of 14th Japan International SAMPE Symposium & Exhibition (JISSE-14) (USB Flash Drive), 6 Pages, 2015/12
Endo, Naruki*; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori
Journal of Alloys and Compounds, 645(Suppl.1), p.S61 - S63, 2015/10
Shimada, Hiroyuki*; Minami, Hirotake*; Okuizumi, Naoto*; Sakuma, Ichiro*; Ukai, Masatoshi*; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro*; Saito, Yuji
Journal of Chemical Physics, 142(17), p.175102_1 - 175102_9, 2015/05
Shimada, Hiroyuki*; Fukao, Taishi*; Minami, Hirotake*; Ukai, Masatoshi*; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro*; Saito, Yuji
Journal of Chemical Physics, 141(5), p.055102_1 - 055102_8, 2014/08
Saito, Hiroyuki; Takagi, Shigeyuki*; Matsuo, Motoaki*; Iijima, Yuki*; Endo, Naruki*; Aoki, Katsutoshi*; Orimo, Shinichi*
APL Materials (Internet), 2(7), p.076103_1 - 076103_7, 2014/07
Okada, Michio*; Moritani, Kosuke; Fukuyama, Tetsuya*; Mizutani, Hironori*; Yoshigoe, Akitaka; Teraoka, Yuden; Kasai, Toshio*
Surface Science, 600(18), p.4228 - 4232, 2006/09
Dissociative adsorption of hyperthermal O molecules on CuAu(100) was investigated by X-ray photoemission spectroscopy in conjunction with a synchrotron light source. Comparing the O-uptake curve on CuAu with that on Cu, it was found that the dissociative adsorption of O is more activated (less reactive) due to Au alloying. The low-energy electron-diffraction (LEED) pattern of c(22) for the clean surface turned into the (11) LEED pattern during the oxidation by hyperthermal O molecular beam, suggesting that the O adsorption induces the Cu-atom segregation on the surface.
Takahashi, Masamitsu; Kratzer, P.*; Penev, E.*; Mizuki, Junichiro
Surface Science, 600(18), p.4099 - 4102, 2006/09
The GaAs(001)-c(44) has been studied by synchrotron surface X-ray diffraction. The atomic coordinates and Debye-Waller factors were determined up to the sixth layer from the surface. The results support the formation of the Ga-As heterodimers. The resultant atomic coordinates were compared with those given by a first-principle calculation. In spite of the theoretical prediction of the stability of the single-heterodimer structure, our data fit best a three-heterodimer model where three heterodimers are present in one unit cell. The preference of the formation of the three heterodimers will be discussed in the relationship with the transition process from the 24 to the c(44) structures.
Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.
Surface and Interface Analysis, 38(4), p.352 - 356, 2006/04
We investigated the orientation nature at the top-most layers of F-irradiated graphite using polarization dependent near-edge X-ray absorption fine structure (NEXAFS) spectroscopy which incorporates partial electron yield (PEY) detection and photon-stimulated ion desorption (PSID) techniques. The fluorine K-edge NEXAFS spectra conducted in PEY mode show no significant dependence on polarization angles. In contrast, NEXAFS spectra recorded in F ion yield mode show enhanced yields at a feature of 689.4 eV assigned as a *(C-F) state relevant to =C-F sites, which depend on polarization angles. The C-F bonds prefer relatively tilting down the surface at the top-most layer, while the C-F bonds are randomly directed at deeper regions. We conclude that the difference in the orientation structures between the top surface and bulk is reflected in the NEXAFS recorded in the two different detection modes. It was also found that H- and F- PSID NEXAFS spectra are helpful in understanding desorption mechanism, thus in analysing NEXAFS data.
Netsu Shori, 46(1), p.11 - 18, 2006/02
no abstracts in English
Tagawa, Masahito*; Sogo, Chie*; Yokota, Kumiko*; Hachiue, Shunsuke; Yoshigoe, Akitaka; Teraoka, Yuden
Japanese Journal of Applied Physics, 44(12), p.8300 - 8304, 2005/12
Si oxide layers formed on Si(001) substrates by irradiation of hyperthermal oxygen atomic beams at room temperature were analysed at the JAERI soft X-ray beamline by photoemission spectroscopy. It was found that sub-oxide components were scarcely observed in the Si oxide layers formed by the atomic oxygen beam.
Liu, J. C.*; Fasso, A.*; Prinz, A.*; Rokni, S.*; Asano, Yoshihiro
Radiation Protection Dosimetry, 116(1-4), p.658 - 661, 2005/12
no abstracts in English
Asano, Yoshihiro; Kawashima, Yoshitaka*
Radiation Protection Dosimetry, 115(1-4), p.176 - 180, 2005/12
no abstracts in English
Otani, Eiji*; Suzuki, Akio*; Ando, Ryota*; Urakawa, Satoru*; Funakoshi, Kenichi*; Katayama, Yoshinori
Advances in High-Pressure Technology for Geophysical Applications, p.195 - 209, 2005/09
This paper summarizes the techniques for the viscosity and density measurements of silicate melt and glasses at high pressure and temperature by using the X-ray radiography and absorption techniques in the third generation synchrotron radiation facility, SPring-8, Japan. The falling sphere method using in situ X-ray radiography makes it possible to measure the viscosity of silicate melts to the pressures above 6 GPa at high temperature. We summarize the details of the experimental technique of the viscosity measurement, and the results of the measurements of some silicate melts such as the albite and diopside-jadeite systems. X-ray absorption method is applied to measure the density of the silicate glasses such as the basaltic glass and iron sodium disilicate glass up to 5 GPa at high temperature. A diamond capsule, which is not reactive with the glass, is used for the density measurement of the glasses. The present density measurement of the glasses indicates that this method is useful for measurement of the density of silicate melts at high pressure and temperature.
Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.*; Uddin, M. N.*
Journal of Physics; Condensed Matter, 17(36), p.5453 - 5466, 2005/09
The orientation nature of multilayer organosilicon compounds has been investigated by measuring the dependence of the Si K-shell near-edge X-ray absorption fine structures (NEXAFS) on the polarization angle. Two approaches helped to elucidate the orientation mechanism: the substitution effect and the deposition-rate dependence. The orientation angles of Si-X bond axes were obtained for trimethylsilyl halides, (CH)SiX (X =F Cl Br I NCO, condensed on Cu(111) at a low (82 K) temperature: the angles are 60, 73, 61, 55, and 55 degrees with respect to the surface normal, for X =F, Cl, Br, I, and NCO, respectively. Chloride (X =Cl) produces the most parallel tilt angle. The specific orientation nature of chloride is attributed to its strong dipole moment as well as the regular tetrahedron shape of the molecule. The molecular volumes calculated verify this view. Furthermore, deposition rates are found to greatly influence the growth manner: namely, high deposition rates led to a slightly perpendicular orientation of Si-X bond axis.