Mechanistic insights into stress-mediated corrosion behavior of basal-textured magnesium alloys

The high electrochemical activity of magnesium alloys, coupled with the non-protective nature of their surface oxides, fundamentally limits their widespread application. Their corrosion behavior has been extensively modeled to elucidate their anti-corrosion mechanisms, yet fails to establish quantitative congruence between simulated and experimental corrosion responses. In this study, mechanistic insight into stress-mediated corrosion behavior of AZ31B magnesium alloys was investigated via a density functional theory (DFT)-based model, integrating hydrogen evolution reaction and anodic dissolution mechanisms. Basal-textured [0002]-oriented magnesium alloys were specially prepared via wire-based friction stir additive manufacturing to ensure the comparability between the atomic-scale model and experimental results. Corrosion response experiments showed a negative shift of corrosion potential from -1.41 V vs. SCE (without external stress) to -1.45 V vs. SCE (with external stress of 120% yield strength), attributed to stress-induced rupture and dissolution of the surface films. The surface oxide film demonstrated self-healing capability, recovering the corrosion potential by 0.20 V after 144 h. DFT-based model achieved exceptional agreement with experimental polarization data, thereby validating its predictive capability for designing corrosion-resistant magnesium alloys.