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Fe
O
and zero-thermal expansion compositeNabetani, Koichiro*; Muramatsu, Yuya*; Oka, Kengo*; Nakano, Kiho*; Hojo, Hajime*; Mizumaki, Masaichiro*; Agui, Akane; Higo, Yuji*; Hayashi, Naoaki*; Takano, Mikio*; et al.
Applied Physics Letters, 106(6), p.061912_1 - 061912_5, 2015/02
Times Cited Count：60 Percentile：89.12(Physics, Applied)Negative thermal expansion (NTE) of BiNi
Fe
O
is investigated by dilatometric curves, synchrotron X-ray diffraction, and X-ray absorption spectroscopy. All samples (x=0.05-0.15) shows large NTE with the coefficient of linear thermal expansion which induced by charge transfer between Bi
and Ni
in the controlled temperature range near room temperature. Compared with BiLnNiO (Ln: rare-earth elements), the thermal hysteresis that causes a problem for practical application is suppressed because random distribution of Fe in the Ni site changes the first order transition to second order-like transition.
Akita, Koichi; Hayashi, Kengo*; Takeda, Kazuya*; Sano, Yuji*; Suzuki, Hiroshi; Moriai, Atsushi; Oya, Shinichi*
Mechanical Engineering Journal (Internet), 1(4), p.SMM0029_1 - SMM0029_8, 2014/08
Compressive residual stresses induced by peening techniques improve the strength properties of steels, such as fatigue and stress corrosion cracking. However, the compressive residual stress might be reduced owing to thermal and mechanical loading in-service. In this study, the behavior of surface and internal residual stresses of a laser-peened ferritic steel under quasi-static tensile loading was investigated by X-ray and neutron diffraction. The complementary use of these diffraction techniques provided decisive experimental evidence for elucidating the relaxation process. The critical applied stress of peened samples subjected to a tensile loading can be estimated from the von Misses yield criterion with the maximum tensile residual stress inside the sample.
P
; Evidence from resonant and nonresonant X-ray diffractionMatsumura, Takeshi*; Michimura, Shinji*; Inami, Toshiya; Hayashi, Yuya*; Fushiya, Kengo*; Matsuda, Tatsuma*; Higashinaka, Ryuji*; Aoki, Yuji*; Sugawara, Hitoshi*
Physical Review B, 89(16), p.161116_1 - 161116_5, 2014/04
Times Cited Count：15 Percentile：54.46(Materials Science, Multidisciplinary)The antiferromagnetic ordered phase below 
= 16.5 K and the unresolved intermediate phase between and 
(= 14 K) in SmRu
P have been studied by resonant and nonresonant X-ray diffraction. In the intermediate phase, nonresonant Thomson scattering with 
= (1,0,0) is induced by applying a magnetic field. This phenomena is caused by atomic displacements reflecting the charge order in the 
band, as predicted theoretically. Simultaneously, the antiferromagnetic moment of Sm is enhanced along the field direction, which is considered to reflect the staggered ordering of the 
- 
crystal-field states. The present results show that the orbital-dependent - 
hybridization in association with the nesting instability in the band gives rise to the unconventional charge order similarly with PrRuP and PrFeP.
Yamawaki, Michio*; Luo, G.*; Shibuya, Kengo*; Yamaguchi, Kenji*; Hayashi, Kimio
Tokyo Daigaku Kogakubu Sogo Shikenjo Nempo, 59, p.105 - 110, 2000/12
no abstracts in English
Akita, Koichi; Hayashi, Kengo*; Takeda, Kazuya*; Sano, Yuji*; Oya, Shinichi*
no journal, ,
Relaxation process of peening residual stress under mechanical loading was investigated by neutron stress measurement method. Relaxation of the surface compressive residual stress was started before the stress of the surface layer reached the yield stress, which would be caused by the re-distribution of the residual stress due to the plastic deformation of the center region. Therefore, the understanding of the magnitude of balancing tensile residual stress is important to evaluate the relaxation of the surface compressive residual stress against tensile applied stress.
