Corrosion behavior of three nickel-based single-crystal superalloys in mixed Na₂SO₄ and NaCl molten salts at 700 °C

Abstract

In this investigation, we examined the high-temperature corrosion behavior of three nickel-based single-crystal superalloys subjected to a mixed molten salt environment of Na₂SO₄ and NaCl at 700 °C, leading to a preliminary elucidation of their molten salt corrosion mechanisms. By further comparing the corrosion degree of the three nickelbased single-crystal superalloys combined with the Gibbs free energy calculation of the corrosion products, the influence of alloying elements on the corrosion performance of nickel-based single-crystal superalloys was analyzed. It was established that the corrosion mechanism of these nickel-based single-crystal superalloys predominantly involves a cyclic process of oxide layer formation and decomposition, ultimately resulting in the establishment of a protective layer principally composed of NiO, with a constantly regenerating Al₂O₃ barrier, impeding further alloy degradation. Furthermore, the inclusion of elements such as Cr, Al, Ta, and notably Re has been found to markedly improve the thermal corrosion resistance of the superalloys. These insights not only enhance our comprehension of the corrosion mechanisms pertinent to nickel-based superalloys, but also provide strategic directions for alloy composition refinement aimed at bolstering their corrosion resilience.

Keywords

superalloys / Ni-based alloy / hot salt corrosion / corrosion in marine environments

References

[1] Reed R C, Tao T, Warnken N. Alloys-by-design: Application to nickel-based single crystal superalloys [J]. Acta Materialia, 2009, 57(19): 5898-5913

[2] Hashizume R, Yoshinari A, Kiyono T, et al.. Development of novel Ni-based single crystal superalloys for power-generation gas turbines [J]. Materials at High Temperatures, 2007, 24(3): 163-172

[3] Yao J, Luo Y-w, Wang J-c, et al.. Machine learning guided insights into the effects of Nb/Ta and Ti/Ta ratios on microstructure and creep rupture life in nickelbased single-crystal superalloys [J]. Metals and Materials International, 2025, 31(9): 2710-2729

[4] SU Jie, WANG Jun-cheng, WU Jun-kang, et al. Effect of inclination angle on microstructural evolution and mechanical property of support-free IN718 alloy fabricated by selective laser melting [J]. Metals and Materials International, 2025. DOI: https://doi.org/10.1007/s12540-025-01915-w.

[5] Chang J X, Wang D, Liu X G, et al.. Effect of rhenium addition on hot corrosion resistance of Ni-based single crystal superalloys [J]. Metallurgical and Materials Transactions A, 2018, 49(9): 4343-4352

[6] Tao X-c, Lou Y-m, Li M-l, et al.. Microstructure and mechanical properties of VAlN/Si₃N₄ nano-multilayer coatings [J]. Journal of Central South University, 2022, 29(5): 1403-1411

[7] Dai Y-z, Zou J-p, Ning X-z, et al.. Microstructure evolution and oxidation behavior of silicon-modified aluminide coatings on IN718 superalloy at 1000 °C [J]. Journal of Central South University, 2024, 31(5): 1426-1442

[8] Xie J, Shu D-l, Hou G-c, et al.. Low-cycle fatigue behavior of K416B Ni-based superalloy at 650 °C [J]. Journal of Central South University, 2021, 28(9): 2628-2635

[9] Zheng D-y, Xia Y-f, Teng H-h, et al.. Application of genetic algorithm to enhance the predictive stability of BP-ANN constitutive model for GH4169 superalloy [J]. Journal of Central South University, 2024, 31(3): 693-708

[10] Wang Y-j, Jia Z, Gao Z-x, et al.. Continuous dynamic recrystallization nucleation mechanism and annealing twin evolution with respect to grain growth in a nickel-based superalloy [J]. Journal of Central South University, 2023, 30(1): 49-60

[11] Song P, Liu M-f, Jiang X-w, et al.. Influence of alloying elements on hot corrosion resistance of nickel-based single crystal superalloys coated with Na₂SO₄ salt at 900 °C [J]. Materials & Design, 2021, 197: 109197

[12] Li Q-y, Liu F, Li Y-x, et al.. A study of the hot salt corrosion behavior of three nickel-based single-crystal superalloys at 900 °C [J]. Crystals, 2024, 14(4): 307

[13] Wan L, Zhang Z-y, Wang W-q, et al.. Research on hot corrosion behavior of DZ40M and K452 superalloys in NaCl molten salt [J]. Materials, 2022, 15(41512

[14] Jiang H, Dong J-x, Zhang M-c, et al.. Hot corrosion behavior and mechanism of FGH96 P/M superalloy in molten NaCl-Na₂SO₄ salts [J]. Rare Metals, 2019, 38(2173-180

[15] Wang X-y, Liu Z-d, Cheng K-h, et al.. Corrosion characteristics of Inconel 625 cladding layer and NiCrMoAl cladding layer in molten NaCl-KCl and NaCl-KCl-Na₂SO₄ [J]. Corrosion Science, 2023, 221: 111308

[16] Wei B-x, Chen C-j, Xu J, et al.. Comparing the hot corrosion of (100), (210) and (110) Ni-based superalloys exposed to the mixed salt of Na₂SO₄-NaCl at 750 °C: Experimental study and first-principles calculation [J]. Corrosion Science, 2022, 195: 109996

[17] Zhang X, Wan J-c, Zhu L, et al.. Influence of Nb on the hot corrosion behaviors of a Fe-Cr-Ni heat-resistant steel weld metal in the Na₂SO₄-NaCl molten salt at 700 °C [J]. Metals and Materials International, 2023, 29(123645-3654

[18] Wang X-y, Liu Z-d, Cheng K-h, et al.. Chlorine-induced high-temperature corrosion characteristics of Ni-Cr alloy cladding layer and Ni-Cr-Mo alloy cladding layer [J]. Corrosion Science, 2023, 216: 111102

[19] Yang Y Q, Zhao Y C, Wen Z X, et al.. Synergistic effect of multiple molten salts on hot corrosion behaviour of Ni-based single crystal superalloy [J]. Corrosion Science, 2022, 204: 110381

[20] Chen Z-h, Qu W-w, Zhang Z-l, et al.. Hot corrosion mechanism of nickel-based single crystal superalloy IC21 under flowing atmosphere [J]. Corrosion Science, 2023, 218: 111170

[21] Li M-f, Henein H, Zhou C-g, et al.. Towards high-entropy alloys with high-temperature corrosion resistance and structural stability [J]. Journal of Materials Science & Technology, 2024, 174: 133-144

[22] Stringer J. High-temperature corrosion of superalloys [J]. Materials Science and Technology, 1987, 3(7482-493

[23] Chen Z-h, Li S-s, Wu M-m, et al.. Effects of different surface native pre-oxides on the hot corrosion properties of nickel-based single crystal superalloys [J]. Materials, 2020, 13(24): 5774

[24] Lee W Y, Bae Y W, Stinton D E. Na₂SO₄-induced corrosion of Si₃N₄ coated with chemically vapor deposited Ta₂O₅ [J]. Journal of the American Ceramic Society, 1995, 78(71927-1930

[25] Chang J X, Wang D, Zhang G, et al.. Interaction of Ta and Cr on Type-I hot corrosion resistance of single crystal Ni-base superalloys [J]. Corrosion Science, 2017, 117: 35-42

[26] Rapp R A. Chemistry and electrochemistry of the hot corrosion of metals [J]. Corrosion, 1987, 42(10): 568-577

[27] Rapp R A. Hot corrosion of materials: A fluxing mechanism? [J]. Corrosion Science, 2002, 44(2): 209-221

[28] Hwang Y S, Rapp R A. Synergistic dissolution of oxides in molten sodium sulfate [J]. Journal of the Electrochemical Society, 1990, 137(4): 1276-1280

[29] Rapp R A, Zhang Y-shu. Hot corrosion of materials: Fundamental studies [J]. JOM, 1994, 46(12): 47-55

[30] Shu Y-h, Wang F-h, Wu W-tao. Synergistic effect of NaCl and water vapor on the corrosion of 1Cr-11Ni-2W-2Mo-V steel at 500–700° [J]. Oxidation of Metals, 1999, 51(1): 97-110

[31] Birks N, Meier G H, Pettit F S. Introduction to the high temperature oxidation of metals [M], 2006, Cambridge, Cambridge University Press

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