Influence of hydrogen on the damage behavior of IMC particles in Al-Zn-Mg-Cu alloys

In recent years, it has been reported that intermetallic compound particles can suppress hydrogen embrittlement by hydrogen trapping into them. Some intermetallic particles in aluminum alloys, such as Al₇Cu₂Fe, have internal hydrogen trap sites and it is proposed that hydrogen embrittlement can be suppressed by preferential hydrogen partitioning to these sites. However, intermetallic compound particles act as fracture origin, and excessive addition degrades the mechanical properties. In this study, we quantitatively evaluated the damage and decohesion behavior of intermetallic compound particles in high-hydrogen 7XXX aluminum alloys by using in-situ synchrotron radiation X-ray tomography. As the results, it has been revealed that hydrogen induced early high-strain localization, and the Al₇Cu₂Fe particles were damaged in that region due to own brittleness, resulting in early fracture. Hydrogen had no effect on the fracture and debonding behavior of intermetallic compound particles, suggesting that observed brittle fracture of particles is dependent on the mechanical properties of the particles.