Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 27, 2023 - September 29, 2023
We have shown from first-principles calculations that hydrogen concentration at the interface between the aged precipitate particles (η phase (MgZn2), which is the strengthening phase of the Al-Zn-Mg alloy, causes semi-spontaneous interfacial debonding. Although this debonding of the precipitate is proposed as the mechanism of hydrogen-induced quasi-cleavage fracture, we have yet to directly observe actual interfacial debonding. It is also unclear how interface debonding leads to micro-damage. In this study, we will experimentally clarify the relationship between nano-scale behavior such as interface debonding and macro-scale hydrogen embrittlement such as crack propagation. A black nanovoid-like contrast was observed just below the fracture surface in the vicinity of a white contrast, which is a Zn-rich small particle. Comparing the region just below the fracture surface and the region 500 nm away from the fracture surface, more nanovoids were observed just below the fracture surface. The formation of quasi-cleavage fracture surfaces due to hydrogen embrittlement would be affected by nanovoids.
