Influence of nanovoids in the hydrogen embrittlement fracture of Al–Zn–Mg–Cu alloys

Al–Zn–Mg alloys are representative high-strength aluminum alloys, but hydrogen embrittlement hinders further strengthening. The role of nanovoids in the hydrogen embrittlement of a hydrogen-charged Al–Zn–Mg–Cu alloy is examined using high-resolution imaging-type synchrotron X-ray tomography. Although nanovoids are initiated during deformation, their growth and coalescence behaviors are limited. Hydrogen partitioning analysis indicates that this is because most of the formed vacancies are not stabilized because of the low hydrogen occupancy. Furthermore, 3D/4D clustering analyses of nanovoids reveal that they do not aggregate on a specific plane to initiate a crack, and that linkage between nanovoids is less likely to occur.