Strain analysis of thermoelectric materials using high-resolution synchrotron X-ray diffraction data

Nakasawa, Hayato*; Shobu, Takahisa; Tominaga, Aki; Fujii, Masashi*; Matsumoto, Hironari*; Matsuda, Michiko*; Shimada, Takeshi*; Trivedi, V.*; Tachibana, Makoto*; Tsujii, Naohito*; et al.

Funtai Oyobi Fummatsu Yakin, 72(Suppl.), p.S997 - S1001, 2025/03

https://doi.org/10.2497/jjspm.15P-T21-07

Stress and plastic strain partitioning behaviors and those contributions to martensitic transformation of retained austenite in medium manganese and transformation-induced plasticity-aided bainitic ferrite steels

Hojo, Tomohiko*; Koyama, Motomichi*; Kumai, Bakuya*; Zhou, Y.*; Shibayama, Yuki; Shiro, Ayumi*; Shobu, Takahisa; Saito, Hiroyuki*; Ajita, Saya*; Akiyama, Eiji*

ISIJ International, 65(2), p.284 - 296, 2025/02

https://doi.org/10.2355/isijinternational.ISIJINT-2024-268

In-situ X-ray imaging of the breakup dynamics of current-carrying molten metal jets during arc discharge

Sato, Yuriko*; Shobu, Takahisa; Tominaga, Aki; Sano, Tomokazu*; Ogino, Yosuke*

Communications Materials (Internet), 5, p.147_1 - 147_9, 2024/08

https://doi.org/10.1038/s43246-024-00586-1

The flow dynamics of current-carrying molten metal jet breakup during arc discharge serves as mass and heat sources in wire-arc-based metal deposition processes, thereby optimizing the resultant product quality. However, the spatiotemporal flow interaction between the molten metal jet and the surrounding arc plasma remains unclear. Here, using in-situ synchrotron X-ray imaging, we simultaneously track surface deformation and internal flow in molten aluminum jets during argon arc discharge. We reveal that modulating the magnitude and path of the arc discharge current can accelerate the jet velocity by 200 300% beyond its initial injection speed, thereby facilitating significant jet elongation. Our results provide consistent evidence that the jet flow dynamics are predominantly governed by the interaction between the arc discharge current and its coaxial self-induced magnetic field. This study establishes a framework at the intersection of fluid dynamics and electromagnetism, contributing to optimized control and precision in wire-arc-based applications.

Gradient residual strain measurement procedure in surface impacted railway steel axles by using neutron scattering

Zhou, L.*; Zhang, H.*; Qin, T. Y.*; Hu, F. F.*; Xu, P. G.; Ao, N.*; Su, Y. H.; He, L. H.*; Li, X. H.*; Zhang, J. R.*; et al.

Metallurgical and Materials Transactions A, 55(7), p.2175 - 2185, 2024/07

https://doi.org/10.1007/s11661-024-07352-5

Observation of high-pressure polymorphs in bulk silicon formed at relativistic laser intensities

Rapp, L.*; Matsuoka, Takeshi*; Firestein, K. L.*; Sagae, Daisuke*; Habara, Hideaki*; Mukai, Keiichiro*; Tanaka, Kazuo*; Gamaly, E. G.*; Kodama, Ryosuke*; Seto, Yusuke*; et al.

Physical Review Research (Internet), 6(2), p.023101_1 - 023101_18, 2024/04

https://doi.org/10.1103/PhysRevResearch.6.023101

It is generally known that irradiating a solid surface with a laser pulse of ultra-relativistic intensity generates a plasma on the surface, which in turn creates an ultrahigh pressure inside. In this study, the crystal structure analysis of high-pressure phases generated inside silicon single-crystals irradiated by this laser was performed using the diffraction system at the Stress and Imaging apparatus of BL22XU, which is a JAEA-BL. The results obtained confirm the existence of high-pressure phases that silicon is said to possess: body-centered, rhombohedral, hexagonal, and tetragonal phases in the interior. We can get the results that the crystal structure of silicon polymorphs of being include body-centered, rhombohedral, hexagonal-diamond, tetragonal exists. In the future, we will accumulate data and apply them to control the internal structure, strength, and functionality of materials.

Stress measurement of stainless steel piping welds by complementary use of high-energy synchrotron X-rays and neutrons

Miura, Yasufumi*; Suzuki, Kenji*; Morooka, Satoshi; Shobu, Takahisa

Quantum Beam Science (Internet), 8(1), p.1_1 - 1_14, 2024/03

https://doi.org/10.3390/qubs8010001

Current status of experimental research that contributes to ensuring the quality of post-installed anchors using neutron beams

Mukai, Tomohisa*; Shobu, Takahisa

Kenchiku Bosai, (553), p.6 - 10, 2024/02

no abstracts in English

Characteristic microstructural phase evolution and the compressive strength development mechanisms of tricalcium silicate pastes under various initial carbonation curing environments

Cho, S.*; Suh, H.*; Im, S.*; Kim, G.*; Kanematsu, Manabu*; Morooka, Satoshi; Machida, Akihiko*; Shobu, Takahisa; Bae, S.*

Construction and Building Materials, 409, p.133866_1 - 133866_20, 2023/12

https://doi.org/10.1016/j.conbuildmat.2023.133866

In-operando distribution measurement of internal temperature and stress in lithium-ion battery

Hirano, Tatsumi*; Maeda, Takehiro*; Murata, Tetsuyuki*; Yamamoto, Takahiro*; Matsubara, Eiichiro*; Shobu, Takahisa; Shiro, Ayumi*; Yasuda, Ryo*; Takamatsu, Daiko*

SPring-8/SACLA Riyo Kenkyu Seikashu (Internet), 11(5), p.345 - 353, 2023/10

https://doi.org/10.18957/rr.11.5.345

no abstracts in English

Deformation mechanism of a strong and ductile maraging steel investigated using X-ray synchrotron diffraction

Li, H.*; Liu, Y.*; Zhao, W.*; Liu, B.*; Tominaga, Aki; Shobu, Takahisa; Wei, D.*

International Journal of Plasticity, 165, p.103612_1 - 103612_20, 2023/06

https://doi.org/10.1016/j.ijplas.2023.103612

In order to clarify the strength properties of Co-free maraging steel, tensile experiment using high energy synchrotron X-ray diffraction was performed. Diffraction profiles from the martensitic and austenitic phases were obtained, and their strength and width were observed to vary as loading. Analysis of the diffraction profiles showed that the content of martensite in the as-aged material decreased slowly at low stress levels and decreased rapidly at high stress levels. On the other hand, the austenite phase in the as-solution materials was significantly transformed the martensite phase as the stress increased. It was clarified to be responsible for their respective strength properties.