Study on the salt-corrosion and oxidation role mechanism of Ni-based single crystal superalloy in the long-term hot corrosion environment

Abstract

Hot corrosion is one of the key factors affecting the long-term service of Ni-based single crystal superalloys. In this paper, the long-term hot corrosion test of a second-generation Ni-based single crystal superalloy was carried out in a high-temperature furnace. Then, the microstructure morphology and composition of the alloy were analyzed by a series of characterization methods, which clarified the evolution process of the corrosion/oxidation layer and the attack of the corrosive salt. Meanwhile, EBSD analysis revealed that recrystallization was formed on the γ′-depleted layer, accelerating the cross-section evolution of the alloy. Finally, the effects of Al element content and salt amount on the hot corrosion behavior were investigated separately by the ingenious design of two groups of control tests, and the long-term hot corrosion behavior of Ni-based single crystal superalloys is investigated by decomposition into salt-corrosion damage and alloy-oxidation protection behavior for the first time. Further, the salt corrosion-oxidation role mechanism of Ni-based single crystal superalloy in the long-term hot corrosion environment was revealed.

Keywords

• Hot corrosion
• Ni-based single crystal superalloy
• Recrystallization
• Protective oxide layer
• Mechanism of the salt-corrosion and oxidation role