Corrosion Behavior in Acid and Alkaline Medium of TZM Alloy

The corrosion behaviors of TZM and La doped TZM alloy in acid and alkaline medium were investigated. Four corrosion period stages as 10, 30, 50, 70 d were designed, and the mass loss condition, weight loss condition, average corrosion rate and corrosion morphology were investigated and compared. The corrosion mechanism in acid and alkaline of TZM alloy and the effect of La doping on corrosion resistance of TZM alloy were analyzed. The results show that TZM alloy corroded in acid sets off cell reaction and anode dissolves with cathode hydrogen evolution. Corrosion prior occurs at the surface defect, impurity, grain boundary and dislocation. Crevice corrosion morphology is observed at the narrow slit which is formed by scratch and width less than 0.00254 mm. Corrosion hardly occurs in alkaline medium. La doping could slightly promote the corrosion resistance of TZM alloy, but the improvement is not significant.