Revisiting hydrogen trapping in Mg(Al, Zn) Approximant crystal; Influence of chemical disorder

Shimizu, Kazuyuki*; Yamaguchi, Masatake; Akamaru, Satoshi*; Nishimura, Katsuhiko*; Abe, Rion*; Sasaki, Taisuke*; Wang, Y.*; Toda, Hiroyuki*

Scripta Materialia, 265, p.116730_1 - 116730_7, 2025/08

https://doi.org/10.1016/j.scriptamat.2025.116730

Hydrogen embrittlement in Al-Zn-Mg alloys; Semispontaneous decohesion of precipitates

Shimizu, Kazuyuki*; Toda, Hiroyuki*; Hirayama, Kyosuke*; Fujihara, Hiro*; Tsuru, Tomohito; Yamaguchi, Masatake; Sasaki, Taisuke*; Uesugi, Masayuki*; Takeuchi, Akihisa*

International Journal of Hydrogen Energy, 109, p.1421 - 1436, 2025/03

https://doi.org/10.1016/j.ijhydene.2025.02.123

Our preceding investigation revealed that multiple hydrogen traps at coherent interfaces of MgZn precipitates initiated spontaneous interface decohesion, causing hydrogen-induced quasicleavage cracking in Al-Zn-Mg alloys. Herein, we performed a quantitative and systematic investigation to discern the mechanisms by which hydrogen trapped at coherent/semi-coherent interfaces of precipitates could influence macroscopic hydrogen embrittlement by modulating the coherent interface of MgZn through aging. To explore this hydrogen embrittlement phenomenon based on hydrogen trapping at the precipitate interface, we determined the hydrogen trapping energy of the semi-coherent MgZn interface via first-principles calculations (0.56 eV/atom). Hydrogen partitioning of all hydrogen trapping sites, including vacancies, grain boundaries, and coherent and semi-coherent MgZn interfaces, revealed that in overaged alloys, over 90% of the hydrogen was sequestered at semi-coherent interfaces. Owing to the inherent characteristics of the MgZn interface, the hydrogen sequestered at the semi-coherent interface decreased the interfacial cohesive energy, causing semispontaneous decohesion of the interface and quasicleavage fracture in the Al-Zn-Mg alloys. These results implied that intergranular fracture was not directly induced by hydrogen trapped at grain boundaries but rather by the decohesion of precipitate interfaces along grain boundaries.

Morphology evolution of -phase in Al-Mg-Si alloys during aging treatment

Ahmed, A.*; Uttarasak, K.*; Tsuchiya, Taiki*; Lee, S.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Toda, Hiroyuki*; Yamaguchi, Masatake; et al.

Journal of Alloys and Compounds, 988, p.174234_1 - 174234_9, 2024/06

https://doi.org/10.1016/j.jallcom.2024.174234

This study aims to clarify the growth process of the-phase in Al-Mg-Si alloys from the point of view of morphology evolution. For this research, the -phase orientation relationship, shape, growth process, misfit value, and interfacial condition between the -phase and Al matrix were investigated using high-resolution transmission electron microscopy (HR-TEM), focus ion beam (FIB), and optical microscope (OM). Results include the identification of {111} facets at the edges of the -phase, as well as the proposal of two new three-dimensional shapes for the -phase. We purposed the morphology evolution during the growth process of MgSi crystal and calculated the misfit to understand the unstable (111) facet has a higher misfit value as compared to the (001) and (011) facets. Our observations provide how they influence the behavior of MgSi crystals.

Identification of hydrogen trapping in aluminum alloys muon spin relaxation method and first-principles calculations

Tsuru, Tomohito; Nishimura, Katsuhiko*; Matsuda, Kenji*; Nunomura, Norio*; Namiki, Takahiro*; Lee, S.*; Higemoto, Wataru; Matsuzaki, Teiichiro*; Yamaguchi, Masatake; Ebihara, Kenichi; et al.

Metallurgical and Materials Transactions A, 54(6), p.2374 - 2383, 2023/06

https://doi.org/10.1007/s11661-023-07024-w

Although hydrogen embrittlement susceptibility of high-strength Al alloys is recognized as a critical issue in the practical use of Al alloys, identifying the hydrogen trapping or distribution has been challenging. In the present study, an effective approach based on experiment and simulation is proposed to explore the potential trap sites in Al alloys. Zero-field muon spin relaxation experiments were carried out for Al-0.5%Mg, Al-0.2%Cu, Al-0.15%Ti, Al-0.011%Ti, Al-0.28%V, and Al-0.015%V (at.%) in the temperature range from 5 to 300 K. The temperature variations of the dipole field widths have revealed three peaks for Al-0.5%Mg, four peaks for Al-0.2%Cu, three peaks for Al-0.011%Ti and Al-0.015%V. Atomic configurations of the muon trapping sites corresponding to the observed peaks are well assigned using the first-principles calculations for the trap energies of hydrogen around a solute and solute-vacancy pair. The extracted linear relationship between the muon peak temperature and the trap energy enables us to explore the potential alloying elements and their complex that have strong binding energies with hydrogen in Al alloys.

Kinetics of the interfacial curing reaction for an epoxy-amine mixture

Yamaguchi, Ko*; Kawaguchi, Daisuke*; Miyata, Noboru*; Miyazaki, Tsukasa*; Aoki, Hiroyuki; Yamamoto, Satoru*; Tanaka, Keiji*

Physical Chemistry Chemical Physics, 24(36), p.21578 - 21582, 2022/09

https://doi.org/10.1039/D2CP03394A

Masses of exotic nuclei

Yamaguchi, Takayuki*; Koura, Hiroyuki; Litvinov, Yu. A.*; Wang, M.*

Progress in Particle and Nuclear Physics, 120, p.103882_1 - 103882_98, 2021/09

https://doi.org/10.1016/j.ppnp.2021.103882

Spontaneous debonding behaviour of reinforcement fine particles in aluminium; Toward high-strength metallic materials development

Toda, Hiroyuki*; Tsuru, Tomohito; Yamaguchi, Masatake; Matsuda, Kenji*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*

Kagaku, 75(10), p.48 - 53, 2020/10

Highly-concentrated precipitations play therefore dominant role in mechanical properties and hydrogen embrittlement of aluminum alloys. It has been considered that the coherent interface between matrix and precipitation does not contribute to the crack initiation and embrittlement due to its coherency. Here, we discovered the origin of unprecedented quasi-cleavage fracture mode. Hydrogen partitioning at various defect sites is investigated comprehensively combined with experiment, theory and first-principles calculations. We demonstrate that despite low excess free volume, the aluminum-precipitation interface is more preferable trap site than void and grain boundary. The cohesivity of the interface deteriorates significantly with increasing occupancy while hydrogen atoms are trapped stably up to extremely high occupancy equivalent to spontaneous cleavage.

Non-invasive imaging of radiocesium dynamics in a living animal using a positron-emitting Cs tracer

Suzui, Nobuo*; Shibata, Takuya; Yin, Y.-G.*; Funaki, Yoshihito*; Kurita, Keisuke; Hoshina, Hiroyuki*; Yamaguchi, Mitsutaka*; Fujimaki, Shu*; Seko, Noriaki*; Watabe, Hiroshi*; et al.

Scientific Reports (Internet), 10, p.16155_1 - 16155_9, 2020/10

https://doi.org/10.1038/s41598-020-73351-2

Hydrogen-accelerated spontaneous microcracking in high-strength aluminium alloys

Tsuru, Tomohito; Shimizu, Kazuyuki*; Yamaguchi, Masatake; Itakura, Mitsuhiro; Ebihara, Kenichi; Bendo, A.*; Matsuda, Kenji*; Toda, Hiroyuki*

Scientific Reports (Internet), 10, p.1998_1 - 1998_8, 2020/04

https://doi.org/10.1038/s41598-020-58834-6

Age-hardening has been one and only process to achieve high strength aluminum alloys since unlike iron and titanium, pure aluminum does not have other solid phases during heat treatment. Highly-concentrated precipitations play therefore dominant role in mechanical properties and hydrogen embrittlement of aluminium alloys. It has been considered that the coherent interface between matrix and precipitation does not contribute to the crack initiation and embrittlement due to its coherency. Here, we discovered the origin of unprecedented quasi-cleavage fracture mode. Hydrogen partitioning at various defect sites is investigated comprehensively combined with experiment, theory and first-principles calculations. We demonstrate that despite low excess free volume, the aluminum-precipitation interface is more preferable trap site than void and grain boundary. The cohesivity of the interface deteriorates significantly with increasing occupancy while hydrogen atoms are trapped stably up to extremely high occupancy equivalent to spontaneous cleavage.

Effect of copper addition on precipitation behavior near grain boundary in Al-Zn-Mg alloy

Matsuda, Kenji*; Yasumoto, Toru*; Bendo, A.*; Tsuchiya, Taiki*; Lee, S.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Marioara, C. D.*; Lervik, A.*; Holmestad, R.*; et al.

Materials Transactions, 60(8), p.1688 - 1696, 2019/08

https://doi.org/10.2320/matertrans.L-M2019828

no abstracts in English