Figure 1
From: Hydrogen-accelerated spontaneous microcracking in high-strength aluminium alloys
Experimental observation of the fracture surface of an Al-Zn-Mg alloy. (a) Three-dimensional tomographic images of fractured Al-Zn-Mg alloy samples captured by synchrotron X-ray tomography. Two fracture modes – intergranular fracture (IGF) and quasi-cleavage fracture (QCF) – can be observed on the fracture surface. Crack propagation can be also captured by tomographic image on the right, where the image was obrained at ε = 11% (near τUTS). The crack is found to propagate gradually and undulatory along various quasi-cleavage facets at which hydrogen atoms are sufficiently trapped. (b) Low-voltage SEM images of this fracture surface, in which very dense white and black dots correspond to an MgZn2 precipitate and the crater of the precipitate, respectively. (c) EDS mapping of Zn and Mg on the fracture surface, indicating a clear region of precipitate.
