4D hydrogen embrittlement behaviour in high strength aluminium alloy

X-ray microtomography technique was used to observe hydrogen-induced strain localization, nano void formation and brittle fracture behaviour in a model Al-Zn-Mg ternary alloy. The alloy exhibited remarkable hydrogen embrittlement during an ordinary tensile test due to hydrogen uptake during its electro discharge machining. Very sharp cracks of about 1-2 m in CTOD were initiated and propagated after characteristic intense strain localization is observed, which we measured in a series of tomographic volumes by tracking tens of thousands of microstructural features. It is noteworthy that hydrostatic expansion was observed where the strain localisation was observed. This expansion was attributable to the formation of high density nano voids by utilizing the ultra-high magnification X-ray microscopy at a synchrotron radiation facility combined with STEM-HAADF observation.