Accelerated recovery of passive oxide films during alternating dissolution–passivation on grain-refined rolled Zr alloys

Deformation processing is essential for Zr alloys as potential structural materials for reprocessing of spent nuclear fuel. Rolled Zr-1.0Ti-0.2Nb alloys with different thickness (20 mm, 10 mm, and 5 mm) were fabricated to reveal effects of deformation degree on corrosion behavior in 12 M HNO₃ at 95 ℃. Generally, increasing deformation degree gradually strengthens corrosion resistance of alloys, attributed to significantly refined grain size. Owing to the reduced concentration of HNO₃ in gaseous phase, the corrosion rates are higher than those in liquid phase. The 5 mm alloy with a deformation degree of 90% demonstrates a refined grain size of 11.8 μm and achieves low corrosion rates of 0.155 × 10⁻³ and 0.176 × 10⁻³ mm/a in liquid and gaseous phases, respectively. Analysis suggests that refined grain promotes the rapid formation of oxides by increasing diffusion channels of oxygen, and especially accelerates the recovery following damage of oxides films during alternating dissolution–passivation processes. Consequently, even in the gaseous phase, a protective oxide film with considerable thickness forms on the 5 mm alloy, effectively mitigating the dissolution and maintaining superior corrosion resistance. The present work offers new insights into optimizing deformation processing for ZrTiNb alloys with potential applications in reprocessing of spent nuclear fuel.