Analysis of atomistic structural deformation characteristics of calcium silicate hydrate in 53-year-old tricalcium silicate paste using atomic pair distribution function

Bae, S.*; Jee, H.*; Suh, H.*; Kanematsu, Manabu*; Shiro, Ayumi*; Machida, Akihiko*; Watanuki, Tetsu*; Shobu, Takahisa; Morooka, Satoshi; Geng, G.*; et al.

Construction and Building Materials, 237, p.117714_1 - 117714_10, 2020/03

https://doi.org/10.1016/j.conbuildmat.2019.117714

Stress measurement of coarse grains using double exposure method

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi*

Zairyo, 68(4), p.312 - 317, 2019/04

https://doi.org/10.2472/jsms.68.312

Materials after thermal processing such as welding often have coarse grains. To understand the residual stress after processing is very important from the viewpoint of the soundness of the structure. In this study, we proposed a double exposure method that combines a two-dimensional detector and high-energy synchrotron radiation as an X-ray stress measurement method for materials with coarse grains, and confirmed its practicality. As a result of measuring the residual stress of the plastic bending specimen and the indentation specimen of the aluminum alloy (A5052), the effectiveness of this measurement method was clarified because the residual stress distribution was in good agreement with the finite element analysis.

Strain measurement in Ti layers of CFRP/Ti laminates by synchrotron X-ray diffraction

Akita, Koichi; Nakatani, Hayato*; Ogihara, Shinji*; Shobu, Takahisa; Shiro, Ayumi*; Igawa, Naoki; Shimojo, Yutaka

SPring-8/SACLA Riyo Kenkyu Seikashu (Research Report) (Internet), 6(1), p.105 - 108, 2018/01

http://doi.org/10.18957/rr.6.1.105

no abstracts in English

Development of CdTe pixel detectors combined with an aluminum Schottky diode sensor and photon-counting ASICs

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

https://doi.org/10.1088/1748-0221/12/01/C01044

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.

In situ X-ray diffraction study of the oxide formed on alloy 600 in borated and lithiated high-temperature water

Watanabe, Masashi*; Yonezawa, Toshio*; Shobu, Takahisa; Shiro, Ayumi; Shoji, Tetsuo*

Corrosion, 72(9), p.1155 - 1169, 2016/09

https://doi.org/10.5006/1994

Hydrostatic compression behavior and high-pressure stabilized -phase in -based titanium aluminide intermetallics

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

https://doi.org/10.3390/met6070165

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.

Stress evaluation in material with coarse grains using area detector

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Zhang, S.*

Zairyo, 63(7), p.527 - 532, 2014/07

https://doi.org/10.2472/jsms.63.527

The spiral slit-system and DSTM (diffraction spot trace method) are under development in order to evaluate internal stresses of materials with coarse grains. The bending stress in the specimen with coarse grains was measured in order to confirm performance of this advanced spiral slit-system. It was proved that the combination of the advanced spiral slit-system and the DSTM is useful for the internal stress measurement of materials with coarse grains. The welded specimen of a Mg-alloy plate was prepared by melt-run with TIG welding. The residual stress map in the cross-section of the specimen was made using the DSTM. On the other hand, the residual stresses of the welded specimen were simulated by a finite element method. The measured residual stresses were similar to the simulated results, and the residual stresses due to extrusion were measured also using the DSTM. Therefore, the DSTM is suitable for the stress measurement of weld parts.

Residual strain of OFC using synchrotron radiation

Sano, Mutsumi*; Takahashi, Sunao*; Watanabe, Atsuo*; Shiro, Ayumi; Shobu, Takahisa

Materials Science Forum, 777, p.255 - 259, 2014/02

https://doi.org/10.4028/www.scientific.net/MSF.777.255

Evaluation of internal stresses using area detectors

Suzuki, Kenji*; Shobu, Takahisa; Shiro, Ayumi; Toyokawa, Hidenori*

Hozengaku, 11(2), p.99 - 106, 2012/07

http://ci.nii.ac.jp/naid/40019383676

An area detector technique has to be applied to the strain scanning method for materials with coarse grains. A new rotating slit system was designed for a 2-dimensional (2D) detector strain scanning method. The rotating slit system can focus the 2D detector on the center of the goniometer, and the gauge volume is made by the rotating slit system. The stress measurements were examined with the rotating slit and 2D detector. The measured diffraction spots shifted for the 2D strain scanning. The magnitude of the shift of the diffraction spot was very large as compared with the shift due to the strain. This phenomenon was caused by interaction between the gauge volume and the coarse grain. That is a coarse grain effect. To overcome the coarse grain effect, we propose a diffraction spot trace method (DSTM), which is constructed by the rotating slit and the PILATUS detector. The bending stress distribution of the coarse grain aluminum alloy was measured by DSTM. The measured stress was consistent with the applied stress.

Internal strain distribution of laser peened Ti-alloy rod studied by high energy synchrotron radiation X-rays

Shobu, Takahisa; Akita, Koichi; Shiro, Ayumi; Fujishiro, Tomoyuki*; Kiriyama, Koji*; Kumagai, Masayoshi*; Hisamori, Noriyuki*

no journal, ,