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Journal Articles

Numerical verification for the effect of suppressing hydrogen embrittlement by Sn doping in the Al-Zn-Mg alloy

Ebihara, Kenichi; Fujihara, Hiro*; Shimizu, Kazuyuki*; Yamaguchi, Masatake; Toda, Hiroyuki*

International Journal of Hydrogen Energy, 136, p.751 - 756, 2025/06

 Times Cited Count:0

It has been experimentally reported that adding tin (Sn) to high-strength aluminum-zinc-magnesium (Al-Zn-Mg) alloys effectively suppresses hydrogen (H) embrittlement, which may be attributed to H absorption by the second-phase particles of Sn. To verify this fact, a simulation of H entry into the Sn phase in Al was performed using a model based on the reaction-diffusion equation that incorporates the solid solution energy of H evaluated by first-principles calculations. The results showed that the H solid solution site concentration of the second-phase particles must be at least five times higher than that of the Al phase for H absorption by the Sn second-phase particles to suppress H embrittlement. Therefore, the actual H embrittlement suppression effect of Sn second-phase particles is limited, and other factors may influence the suppression of H embrittlement in the experiment.

Journal Articles

Multi-modal 3D image-based simulation of hydrogen embrittlement crack initiation in Al-Zn-Mg alloy

Higa, Ryota*; Fujihara, Hiro*; Toda, Hiroyuki*; Kobayashi, Masakazu*; Ebihara, Kenichi; Takeuchi, Akihisa*

Materials Transactions, 65(8), p.899 - 906, 2024/08

 Times Cited Count:0 Percentile:0.00(Materials Science, Multidisciplinary)

It is indispensable to suppress hydrogen embrittlement (HE) to develop the strength of the Al-Zn-Mg alloy. Because intergranular fracture (IGF) is mainly observed when HE occurs in the alloy, we need to understand the IGF initiation to suppress HE. In the present study, we investigated the stress, strain, and H concentration, which influence the IGF initiation, in actual fractured regions by simulation of a crystal plasticity finite element method and H diffusion analysis in a 3D image-based model, which was created based on 3D polycrystalline microstructure data obtained from X-ray imaging technique. Combining the simulation and in-situ observation of the tensile test sample by X-ray CT, we examined the stress, strain, and H concentration, and discussed the IG crack initiation condition. As a result, it is revealed that stress normal to grain boundary induced by crystal plasticity dominates IG crack initiation while the accumulation of H due to stress has little impact on it.

Journal Articles

Measurement of nuclide production cross sections for GeV-region proton-induced reactions on $$^{rm nat}$$Mg, $$^{rm nat}$$Si, $$^{rm nat}$$Fe, $$^{rm nat}$$Cu, and $$^{rm nat}$$Zn

Sugihara, Kenta*; Meigo, Shinichiro; Iwamoto, Hiroki; Maekawa, Fujio

Nuclear Instruments and Methods in Physics Research B, 549, p.165299_1 - 165299_12, 2024/04

 Times Cited Count:0 Percentile:0.00(Instruments & Instrumentation)

Journal Articles

Assessment of hydrogen embrittlement behavior in Al-Zn-Mg alloy through multi-modal 3D image-based simulation

Fujihara, Hiro*; Toda, Hiroyuki*; Ebihara, Kenichi; Kobayashi, Masakazu*; Mayama, Tsuyoshi*; Hirayama, Kyosuke*; Shimizu, Kazuyuki*; Takeuchi, Akihisa*; Uesugi, Masayuki*

International Journal of Plasticity, 174, p.103897_1 - 103897_22, 2024/03

 Times Cited Count:9 Percentile:93.27(Engineering, Mechanical)

Hydrogen(H) embrittlement in high-strength aluminum(Al) alloys is a crucial problem. H accumulation at the interface of precipitates in Al alloy is considered to cause embrittlement. However, there is no quantitative knowledge regarding the interaction between H distribution and stress field near cracks. In this study, using a multi-modal three-dimensional image-based simulation combining the crystal plasticity finite element method and H diffusion analysis, we tried to capture the stress distribution near the crack, its influence on the H distribution, and the probability of crack initiation in the experimental condition. As a result, it was found that grain boundary cracks transition to quasi-cleavage cracks in the region where the cohesive energy of the semi-coherent interface of MgZn$$_2$$ precipitates decreases due to H accumulation near the tip. We believe the present simulation method successfully bridges nanoscale delamination and macroscale brittle fracture.

Journal Articles

Contributions of multimodal microstructure in the deformation behavior of extruded Mg alloys containing LPSO phase

Hagihara, Koji*; Mayama, Tsuyoshi*; Yamasaki, Michiaki*; Harjo, S.; Tokunaga, Toko*; Yamamoto, Kazuki*; Sugita, Mika*; Aoyama, Kairi*; Gong, W.; Nishimoto, Soya*

International Journal of Plasticity, 173, p.103865_1 - 103865_21, 2024/02

 Times Cited Count:24 Percentile:98.62(Engineering, Mechanical)

Journal Articles

Search for the 6$$alpha$$ condensed state in $$^{24}$$Mg using the $$^{12}$$C+$$^{12}$$C scattering

Fujikawa, Y.*; Kawabata, T.*; Adachi, S.*; Hirose, Kentaro; Makii, Hiroyuki; Nishio, Katsuhisa; Orlandi, R.; Suzaki, Fumi; 13 of others*

Physics Letters B, 848, p.138384_1 - 138384_6, 2024/01

 Times Cited Count:6 Percentile:73.96(Astronomy & Astrophysics)

Journal Articles

Stress corrosion cracking induced by the combination of external and internal hydrogen in Al-Zn-Mg-Cu alloy

Tang, J.*; Wang, Y.*; Fujihara, Hiro*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Ebihara, Kenichi; Takeuchi, Akihisa*; Uesugi, Masayuki*; Toda, Hiroyuki*

Scripta Materialia, 239, p.115804_1 - 115804_5, 2024/01

 Times Cited Count:11 Percentile:80.41(Nanoscience & Nanotechnology)

Stress corrosion cracking (SCC) behaviors induced by the combination of external and internal hydrogen (H) in an Al-Zn-Mg-Cu alloy were systematically investigated via in situ 3D characterization techniques. SCC of the Al-Zn-Mg-Cu alloy could initiate and propagate in the potential crack region where the H concentration exceeded a critical value, in which the nanoscopic H-induced decohesion of $$eta$$-MgZn$$_2$$ precipitates resulted in macroscopic cracking. External H that penetrated the alloy from the environment played a crucial role during the SCC of the Al-Zn-Mg-Cu alloy by generating gradient-distributed H-affected zones near the crack tips, which made Al alloys in water environment more sensitive to SCC. Additionally, the pre-existing internal H was driven toward the crack tips during plastic deformation. It was involved in the SCC and made contributions to both the cracks initiation and propagation.

Journal Articles

Multi-modal 3D image-based simulation of hydrogen embrittlement crack initiation in Al-Zn-Mg alloy

Higa, Ryota*; Fujihara, Hiro*; Toda, Hiroyuki*; Kobayashi, Masakazu*; Ebihara, Kenichi; Takeuchi, Akihisa*

Keikinzoku, 73(11), p.530 - 536, 2023/11

In Al-Zn-Mg alloys, suppression of hydrogen embrittlement is necessary to improve their strength. In this study, the distribution of stress, strain, and hydrogen concentration in the actual fracture region was investigated using the crystal plasticity finite element method and hydrogen diffusion analysis based on a model derived from three-dimensional polycrystalline microstructural data obtained by X-ray CT. In addition, the distributions of stress, strain, and hydrogen concentration were compared with the actual crack initiation behavior by combining in-situ observation of tensile tests using X-ray CT and simulation. The results show that stress loading perpendicular to the grain boundary due to crystal plasticity dominates grain boundary crack initiation. It was also found that internal hydrogen accumulation due to crystal plasticity has little effect on crack initiation.

Journal Articles

Measurement of mechanical behavior of $$^{11}$$B-enriched MgB$$_{2}$$ wire using a pulsed neutron source

Machiya, Shutaro*; Osamura, Kozo*; Hishinuma, Yoshimitsu*; Taniguchi, Hiroyasu*; Harjo, S.; Kawasaki, Takuro

Quantum Beam Science (Internet), 7(4), p.34_1 - 34_17, 2023/10

Journal Articles

Mg-ion storage materials based on MnO$$_{2}$$ frameworks

Shimokawa, Kohei*; Hatakeyama, Takuya*; Li, H.*; Ichitsubo, Tetsu

Current Opinion in Electrochemistry, 38, p.101209_1 - 101209_8, 2023/04

 Times Cited Count:6 Percentile:22.85(Chemistry, Physical)

Journal Articles

Mg-Zn-Mn oxide systems for a rechargeable Mg-battery cathode

Ye, X.*; Shimokawa, Kohei*; Kezuka, Yuto*; Hatakeyama, Takuya*; Li, H.*; Ichitsubo, Tetsu

Journal of Physical Chemistry C, 127(11), p.5210 - 5218, 2023/03

 Times Cited Count:2 Percentile:20.33(Chemistry, Physical)

Journal Articles

Bench-scale injection of magnesium hydroxide encapsulated iron nanoparticles (nFe$$^{0}$$@Mg(OH)$$_{2}$$) into porous media for Cr(VI) removal from groundwater

Maamoun, I.; Falyouna, O.*; Eljamal, R.*; Idham, M. F.*; Tanaka, Kazuya; Eljamal, O.*

Chemical Engineering Journal, 451, Part3, p.138718_1 - 138718_22, 2023/01

 Times Cited Count:46 Percentile:92.38(Engineering, Environmental)

Journal Articles

Destruction of the cosmic $$gamma$$-ray emitter $$^{26}$$Al in massive stars; Study of the key $$^{26}$$Al(n, p) reaction

Lederer-Woods, C.*; Harada, Hideo; Kimura, Atsushi; 121 of others*

Physical Review C, 104(2), p.L022803_1 - L022803_7, 2021/08

 Times Cited Count:8 Percentile:67.39(Physics, Nuclear)

Journal Articles

Quantifying internal strains, stresses, and dislocation density in additively manufactured AlSi10Mg during loading-unloading-reloading deformation

Zhang, X. X.*; Andr$"a$, H.*; Harjo, S.; Gong, W.*; Kawasaki, Takuro; Lutz, A.*; Lahres, M.*

Materials & Design, 198, p.109339_1 - 109339_9, 2021/01

 Times Cited Count:58 Percentile:93.33(Materials Science, Multidisciplinary)

Journal Articles

Preparation, thermoelectric properties, and crystal structure of boron-doped Mg$$_{2}$$Si single crystals

Hayashi, Kei*; Saito, Wataru*; Sugimoto, Kazuya*; Oyama, Kenji*; Hayashi, Koichi*; Happo, Naohisa*; Harada, Masahide; Oikawa, Kenichi; Inamura, Yasuhiro; Miyazaki, Yuzuru*

AIP Advances (Internet), 10(3), p.035115_1 - 035115_7, 2020/03

 Times Cited Count:19 Percentile:68.77(Nanoscience & Nanotechnology)

Journal Articles

Impurity effects in the microscopic elastic properties of polycrystalline Mg-Zn-Y alloys with a synchronised long-period stacking ordered phase

Hosokawa, Shinya*; Kimura, Koji*; Yamasaki, Michiaki*; Kawamura, Yoshihito*; Yoshida, Koji*; Inui, Masanori*; Tsutsui, Satoshi*; Baron, A. Q. R.*; Kawakita, Yukinobu; Ito, Shinichi*

Journal of Alloys and Compounds, 695, p.426 - 432, 2017/02

 Times Cited Count:5 Percentile:22.82(Chemistry, Physical)

Journal Articles

Identification of the crossing point at $$N$$ = 21 between normal and intruder configurations

Lic$u{a}$, R.*; Rotaru, F.*; Borge, M. J. G.*; Gr$'e$vy, S.*; Negoita, F.*; Poves, A.*; Sorlin, O.*; Andreyev, A. N.; Borcea, R.*; Costache, C.*; et al.

Physical Review C, 95(2), p.021301_1 - 021301_6, 2017/02

 Times Cited Count:19 Percentile:79.02(Physics, Nuclear)

Journal Articles

Direct numerical simulation on non-equilibrium superconducting dynamics after neutron capture in MgB$$_{2}$$ superconductor

Machida, Masahiko; Koyama, Tomio*; Kato, Masaru*; Ishida, Takekazu*

Nuclear Instruments and Methods in Physics Research A, 559(2), p.594 - 596, 2006/04

 Times Cited Count:11 Percentile:58.92(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Neutronics assessment of advanced shield materials using metal hydride and borohydride for fusion reactors

Hayashi, Takao; Tobita, Kenji; Nishio, Satoshi; Ikeda, Kazuki*; Nakamori, Yuko*; Orimo, Shinichi*; DEMO Plant Design Team

Fusion Engineering and Design, 81(8-14), p.1285 - 1290, 2006/02

 Times Cited Count:27 Percentile:84.58(Nuclear Science & Technology)

Neutron transport calculations were carried out to evaluate the capability of metal hydrides and borohydrides as an advanced shielding material. Some hydrides indicated considerably higher hydrogen content than polyethylene and solid hydrogen. The hydrogen-rich hydrides show superior neutron shielding capability to the conventional materials. From the temperature dependence of dissociation pressure, ZrH$$_{2}$$ and TiH$$_{2}$$ can be used without releasing hydrogen at the temperature of less than 640 $$^{circ}$$C at 1 atm. ZrH$$_{2}$$ and Mg(BH$$_{4}$$)$$_{2}$$ can reduce the thickness of the shield by 30% and 20% compared to a combination of steel and water, respectively. Mixing some hydrides with F82H produces considerable effects in $$gamma$$-ray shielding. The neutron and $$gamma$$-ray shielding capabilities decrease in order of ZrH$$_{2}$$ $$>$$ Mg(BH$$_{4}$$)$$_{2}$$ and F82H $$>$$ TiH$$_{2}$$ and F82H $$>$$ water and F82H.

Journal Articles

Direct numerical simulations for non-equilibrium superconducting dynamics and related neutron detection in MgB$$_{2}$$

Machida, Masahiko; Koyama, Tomio*; Kato, Masaru*; Ishida, Takekazu*

Physica C, 426-431(1), p.169 - 173, 2005/10

no abstracts in English

102 (Records 1-20 displayed on this page)