Al-Zn-Mg alloys are representative high-strength aluminum alloys and are widely used, however, hydrogen embrittlement hinders further strengthening. In this study, combined X-ray nano/micro-tomography, first-principles simulations,
and transmission electron microscopy were employed to evaluate the hydrogen embrittlement in Al-Zn-Mg alloys. Hydrogen induced flow localization, as well as the initiation and growth of quasi-cleavage crack at the low strain level, are discussed through measuring 3D strain distribution. By applying hydrogen partitioning analysis, the influence of trapped hydrogen in sites such as dislocations, nanovoids, precipitates, and intermetallic particles on the hydrogen embrittlement is studied quantitatively. Three-dimensional hydrogen partitioning analysis has been revealed that the coherent and semi-coherent interfaces of precipitates unexpectedly trap the majority of hydrogen in alloys. Hydrogen accumulation at the precipitate interface cause the spontaneous decohesion, originating quasi-cleavage fracture which had been believed to be attributable to dislocation activity.