Enhancing long-term corrosion resistance of Zn modified high-Mg aluminum alloys through optimized stabilization treatment

Stabilization treatment is an effective way to improve the long-term corrosion resistance of low-Mg content (≤5wt.%) Al alloys due to the formation of discontinuous grain boundary β-Al 3 Mg 2 precipitates. Increasing the Mg content can dramatically improve the strength of the alloy by Mg atom solid solution. However, achieving long-term corrosion resistance of such high-Mg (> 6 wt.%) aluminum alloys still poses a serious challenge. In this study to solve the trade-off between strength and long-term corrosion resistance, a synergistic approach combining Zn microalloying with optimized stabilization treatment parameters is employed to improve the comprehensive performance of Al-7wt.%Mg alloy. The Zn-containing alloy demonstrates enhanced spheroidization of GBPs and reduced Mg content in the matrix, both contributing to superior sensitization annealing performance. Theoretical modeling incorporating grain boundary diffusion mechanism and phase-interface interactions confirms that Zn-containing alloys exhibit a significant reduction in grain boundary phase elongation rate during accelerated sensitization compared with Zn-free counterparts. This research provides critical guidance for developing corrosion-resistant high-Mg aluminum alloys in marine engineering applications. • Zn microalloying combined with appropriate stabilization process achieves good long-term corrosion resistance of high Mg aluminum alloy • After stabilization, Zn-containing alloy exhibits increased spheroidization of the grain boundary precipitates and reduced solid-solution Mg content. • Diffusion modeling calculation confirms grain boundary precipitates elongation rate positively correlates with long-term corrosion resistance.