Novel approach to explore hydrogen trapping sites in aluminum: Integrating Muon spin relaxation with first-principles calculations

• Published in: International journal of hydrogen energy 2024-12, Vol.95, p.292-299
• Main Authors: Shimizu, Kazuyuki, Nishimura, Katsuhiko, Matsuda, Kenji, Nunomura, Norio, Namiki, Takahiro, Tsuchiya, Taiki, Akamaru, Satoshi, Lee, Seungwon, Tsuru, Tomohito, Higemoto, Wataru, Toda, Hiroyuki
• Format: Article
• Language: English
• Subjects: Aluminum alloys; First-principles calculations; Hydrogen; Hydrogen trapping; Muon spin relaxation
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.11.265

This paper provides a novel technique to explore hydrogen trapping in aluminum alloys by combining muon spin relaxation and first-principles calculations. Zero-field muon spin relaxation experiments were conducted on Al–Mn, Al–Cr, Al–Fe, and Al–Ni alloys, resulting in temperature-dependent variations of the dipole field widths (Δ) that elucidated four distinct peaks for the prepared alloys. Our first-principles calculations have clarified that atomic configurations of the muon trapping, which correspond to the Δ peaks below 200 K, are consistent with hydrogen trapping sites in proximity to a solute and solute-vacancy pair. However, significant deviations from this linear relationship were observed for the fourth Δ peaks above 200 K in Al–Mn, Al–Cr, Al–Fe, and Al–Ni alloys. This discrepancy can be interpreted by considering the disparate distribution functions of muon and hydrogen within the tetrahedral site, wherein two of the four Al atoms are substituted by the solute element and vacancy (solute-vacancy pair). [Display omitted] •Combined analysis of muon spin relaxation and first-principles calculations reveal hydrogen trapping in aluminum alloys.•Muons behave as quasi-hydrogen allowing for experimental exploration of hydrogen trapping sites in aluminum.•Solute atoms and solute atom-vacancy pairs trap hydrogen differently depending on the atom type.•Below 200 K, hydrogen and muon trapping show a linear relationship, but deviate above this temperature.