Correlation between the Mg/Si Ratio and Intergranular Corrosion Resistance in Naturally‐Aged 6082‐T6 Aluminum Alloys

This study systematically investigated the regulatory mechanisms of the Mg/Si ratio and natural aging treatment on the characteristics of intergranular precipitates and the intergranular corrosion resistance of 6082 aluminum alloy. Key findings reveal that the alloy with an atomic Mg/Si ratio of 2.0 promoted the coarsening of intergranular precipitates and the formation of continuous chain‐like structures due to solute enrichment, resulting in a broad precipitate‐free zone (PFZ) and a significant electrochemical gradient, which exacerbated intergranular corrosion. The alloy with an atomic Mg/Si ratio of 0.8 utilized the intragranular stable clusters formed during natural aging to preferentially capture solutes, effectively inhibiting the continuity of intergranular precipitates and significantly reducing the PFZ, thereby synergistically optimizing strength and corrosion resistance. The alloy with an atomic Mg/Si ratio of 1.4 avoided continuous nucleation and significant coarsening, forming a discontinuous precipitate distribution, and exhibited relatively excellent corrosion resistance. The research clarifies the cross‐scale mechanism, where the Mg/Si ratio drives the competitive evolution of intragranular and intergranular precipitates through the regulation of solute diffusion kinetics, providing a key theoretical basis for the composition and process design of high‐strength, corrosion‐resistant aluminum alloys.