Metallurgical Abstracts on Light Metals and Alloys vol. 58
Hydrogen embrittlement in Al–Zn–Mg alloys: Semispontaneous decohesion of precipitates
Kazuyuki Shimizu*, Hiroyuki Toda**, Kyosuke Hirayama***, Hiro Fujihara**, Tomohito Tsuru****, Masatake Yamaguchi*****,
Taisuke T. Sasaki*******, Masayuki Uesugi******** and Akihisa Takeuchi********
* Faculty of Engineering, Tottori University
** Department of Mechanical Engineering, Kyushu University
*** Department of Engineering and Design, Kagawa University
**** Nuclear Science Research Center, Japan Atomic Energy Agency
***** Center for Computational Science and e-Systems, Japan Atomic Energy Agency
******* Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science
******** Japan Synchrotron Radiation Research Institute
[Published in International Journal of Hydrogen Energy, Vol. 109 (2025), pp. 1421-1436]
https://doi.org/10.1016/j.ijhydene.2025.02.123
E-mail: ksmz[at]tottori-u.ac.jp
Key Words: Hydrogen embrittlement, Al–Zn–Mg alloys, Aluminum alloys, X-ray tomography, First-principles calculation
Our study investigates how hydrogen trapped at interfaces of MgZn2 precipitates affects hydrogen embrittlement in Al–Zn–Mg alloys. Al–Zn–Mg alloys featuring various aged microstructures were prepared, and their hydrogen embrittlement behaviors were monitored in situ during tensile tests via synchrotron radiation X-ray microtomography. The changes in the interfacial properties of MgZn2 instigated a discernible transition in the quasicleavage and intergranular fractures. First-principles calculations revealed that the hydrogen trapping energy at semicoherent interfaces of MgZn2 is significantly high at 0.56 eV/atom, and multiple hydrogen trapping leads to a substantial reduction in interfacial cohesive energy. Hydrogen partitioning analysis of all trapping sites, including vacancies, grain boundaries, and MgZn2 interfaces, demonstrated that in overaged alloys, more than 90% of the hydrogen was trapped at semicoherent interfaces. The hydrogen trapped at the semicoherent interface of MgZn2 decreased the interfacial cohesive energy, causing semispontaneous decohesion and quasicleavage fracture in the Al–Zn–Mg alloys.
