Crystallographic Analysis of Hydrogen Embrittlement Behavior in Aluminum Alloy using Diffraction Contrast Tomography

Crystallographic assessment of the hydrogen embrittlement behavior of Al-Zn-Mg alloy was performed by means of a technique combining fracture trajectory analysis and synchrotron X-ray diffraction contrast tomography. The 3D microstructure reconstructed using diffraction contrast tomography contained 119 grains. Fracture surfaces revealing intergranular fracture, ductile fracture, and quasi-cleavage fracture were observed in the alloy. While the intergranular crack initiated at a grain boundary with high grain boundary energy and a high angle between the grain boundary plane and loading direction, the crack propagation itself was not observed to be sensitive to these two parameters. The quasi-cleavage fracture surfaces were not characterized by any specific crystal orientation because of variation in the free surface segregation energy of hydrogen uniforms without depending on surface orientation.