The Intergranular Corrosion Resistance Mechanism of High Strength and Ductility AA2024 Aluminum Alloy

ABSTRACT This study utilized a constrained deformation heat treatment to fabricate a multi‐gradient structure in AA2024 aluminum alloy, comprising a surface deformation layer (DL) and a core constraint layer. The material demonstrated a 25.3% increase in yield strength compared to the conventional T6 state, along with a 56.4% reduction in the maximum intergranular corrosion depth. The mechanical enhancement originates from hetero deformation‐induced (HDI) hardening induced by dislocation gradients and high dislocation density. The improved corrosion resistance stems from the unique grain boundary structure within the DL, where alternating high‐angle and low‐angle grain boundaries inhibit continuous grain boundary precipitation. The presence of coincident site lattices at high‐angle grain boundaries further enhances grain boundary chemical stability. Simultaneously, high‐density dislocations promote solute atom diffusion, facilitating S‐phase nucleation along dislocations and resulting in discontinuous distribution along grain boundaries. The synergistic effect of these microstructural characteristics collectively reduces the material's corrosion propensity and propagation rate.