Synergetic effects of pH and F⁻on passive film stability and SCC behavior of Ti-6Al-3Nb-2Zr-1Mo in simulated seawater

This work focuses on the individual and synergistic effects of pH and F⁻on passive film and stress corrosion cracking (SCC) behavior of the Ti-6Al-3Nb-2Zr-1Mo alloy. Results show that H⁺accelerates both cathodic and anodic reactions, though its effect on anodic dissolution is moderate without influencing passive film composition. Conversely, F⁻has a negligible impact on the cathodic reaction but significantly enhances anodic dissolution (AD), increasing film's dissolution rate. Crucially, the coexistence of F⁻and H⁺exhibits a strong synergistic effect, drastically accelerating both anodic dissolution and cathodic reduction rates, thereby intensifying overall corrosion. Furthermore, the combined action of stress with H⁺and F⁻further exacerbates SCC initiation and propagation, which is primarily controlled by AD mechanism.