Nanoscale perspective on the stress-corrosion cracking behavior of a peak-aged 7XXX-Al alloy

High-strength 7xxx Al-alloys are used in aerospace and are expected to be increasingly employed in the automotive sector for "lightweighting" but they can be sensitive to stress-corrosion cracking (SCC) depending on temper and loading conditions. Here, we performed double cantilever beam (DCB) crack growth tests and study at the nanoscale stress-corrosion cracks on two compositional variants of AA7140 from different regions of a thick-plate. We report on precipitate dissolution, matrix solute enrichment near the crack tips and a modified microstructure ahead of the crack. We relate our findings with the SCC behaviour on both samples and propose an array of active mechanisms.