Effect of Intermittent Variable Rate Non-isothermal Aging on the Corrosion Resistance of Al-Zn-Mg-Cu Alloy

To increase Al-Zn-Mg-Cu alloys’ resistance to corrosion, an intermittent variable rate non-isothermal aging is proposed to solve this problem. Through the use of polarization curves, electrochemical impedance spectroscopy, intergranular corrosion (IGC), exfoliation corrosion (EXCO), and transmission electron microscopy, researchers examined the effects of intermittent variable rate non-isothermal aging on the corrosion resistance and microstructure morphology of Al-Zn-Mg-Cu alloy. The results show that when the heating rate before and after intermittent aging is 10 °C/h and 30 °C/h, respectively, the minimum IGC depth of the alloy is 18.9 μm, the slowest corrosion rate is 0.0065 mm/a, and the EXCO grade is P. In addition, the grain boundary precipitation phase of the alloy is intermittently distributed and independently rounded, and the PFZ width is 75.9 nm. It effectively obstructs the anodic corrosion channel, and slows down the corrosion progression. The highest content of Cu ions increases the electrode potential of GBPs and enhances the corrosion resistance of the alloy.