Corrosion mechanisms and oxide film evolution of TA10 alloy in harsh subcritical and supercritical hydrothermal environments

This study investigates the corrosion behavior of TA10 alloy in subcritical and supercritical hydrothermal environments, focusing on the influence of key environmental factors—temperature, initial pH, and dissolved oxygen content—on its corrosion characteristics and mechanisms. The findings reveal that low-temperature alkaline conditions enhance the passivation of TA10 alloy, improving its corrosion resistance. However, under subcritical alkaline conditions, the presence of Cl^- and the dissolution of TiO₂ into Ti(OH)₅^- lead to the most severe corrosion, emphasizing the critical role of pH and chloride ions in corrosion progression. The oxide film of TA10 alloy comprises an outer oxide layer and an inner diffusion layer, with anatase (a-TiO₂) dominating the outer layer under subcritical alkaline conditions. Notably, high temperatures, moderate dissolved oxygen concentrations, and neutral pH conditions facilitate the transformation of anatase to rutile (r-TiO₂), which significantly enhances the corrosion resistance of the alloy. However, excessive dissolved oxygen leads to the delamination of the oxide film, exacerbating corrosion. This work provides new insights into the mechanisms of titanium alloy corrosion in extreme aqueous environments, offering a theoretical foundation for optimizing material selection and operating conditions in subcritical and supercritical water treatment systems.