Effect of silicon on microstructure and stress rupture properties of a corrosion resistant Ni-based superalloy during long term thermal exposure

Liu, T.; Dong, Jianshu; Xie, Guobo; Wang, L.; Lou, Langhong

doi:10.1016/j.msea.2015.11.018

Cited by 24 publications

(14 citation statements)

References 21 publications

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“…When the alloy was exposed to temperatures above 750 °C for a long time, the massive M 6 C carbides were transformed to M 12 C carbides (Figure 3 and Figure 4). The findings in this work are different from the previous studies for the GH3535 alloy exposed at 700 °C with long-term thermal exposure, where two types of carbides coexist in the exposed alloy [11]. …”

Section: Discussioncontrasting

confidence: 99%

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Carbides Evolution in a Ni-16Mo-7Cr Base Superalloy during Long-Term Thermal Exposure

Han

Jiang

et al. 2017

Materials

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The effect of long-term thermal exposure on the carbide evolution in a Ni-16Mo-7Cr base superalloy was investigated. The results show that M12C carbides are mainly precipitated on the grain boundaries during thermal exposure, and the primary massive M6C carbides can be completely transformed to M12C carbides in situ at temperatures above 750 °C for long-term thermal exposure. The transformation from M6C carbides to M12C carbides is attributed to the release of C atoms from M6C, which results in the morphology changes of massive carbides, and stabilization of the sizes of M12C carbides precipitated on the grain boundaries.

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Section: Discussioncontrasting

confidence: 99%

“…When the alloy is subjected to thermal exposure, M 12 C carbides are precipitated on the grain boundaries [7,11]. When the alloy was exposed to temperatures above 750 °C for a long time, the massive M 6 C carbides were transformed to M 12 C carbides (Figure 3 and Figure 4).…”

Section: Discussionmentioning

confidence: 99%

Carbides Evolution in a Ni-16Mo-7Cr Base Superalloy during Long-Term Thermal Exposure

Han

Jiang

et al. 2017

Materials

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“…It can be seen from Figure 4a,b that there is an obvious concentration gradient for element Cr from the surface to the center. This is consistent with other reports regarding the element Cr in Hastelloy-N alloy reacting and dissolving in the molten salt initially to produce a Cr-depleted surface layer [3,28,29]. Meanwhile, Ni and Mo elements are relatively stable; and there are many Mo-enriched peaks corresponding to the presence of M6C particles after corrosion.…”

Section: Corrosion Behaviorsupporting

confidence: 91%

Improvement of Corrosion Resistance of Hastelloy-N Alloy in LiF-NaF-KF Molten Salt by Laser Cladding Pure Metallic Coatings

Zhu

Chen

et al. 2018

Coatings

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The corrosion protection of Hastelloy-N alloy in LiF-NaF-KF (commonly referred to as FLiNaK) molten salt has been developed by pure Ni and Co coatings using the laser cladding technique. An immersion experiment with samples was performed in molten FLiNaK salt at 900 °C for 100 h. It was found that the corrosion rates of the pure Ni-coated specimen and the pure Co-coated specimen are 39.9% and 35.7% of that of Hastelloy-N alloy, respectively. A careful microstructural characterization indicates that a selective dissolution of the elemental Cr occurred in the surface of bare Hastelloy-N alloy, showing a severe intergranular corrosion. For pure metal-coated specimens, in contrast, only metal oxide formed during the laser cladding process dissolved into the molten fluoride salt. The dense pure metal (Ni or Co) coatings exhibit a slightly general corrosion and protect the Hastelloy-N substrate effectively. The possible corrosion mechanism for both coated and uncoated Hastelloy-N under the current experimental condition are discussed in this work.

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“…Ni-Mo-Cr-Fe based superalloy has excellent corrosion resistance and high temperature resistance, which is used as a structural material in nuclear power molten salt breeder reactor environments [1,2]. The structural parts used in molten salt breeder reactors require long-term service, generally more than 30 years.…”

Section: Introductionmentioning

confidence: 99%

Influence Mechanism of Silicon on Carbide Phase Precipitation of a Corrosion Resistance Nickel Based Superalloy

et al. 2020

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The effect of silicon on diffusion behavior of the carbide forming elements in Ni-Mo-Cr-Fe based corrosion-resistant alloy is studied by diffusion couple experiment. One group of diffusion couples are made of the alloy with a different silicon content, another group of diffusion couples are made of pure nickel and the alloy with different silicon content (0Si, 2Si). Two groups of alloys with same silicon content and different carbon content are also prepared, the microstructure of solution and aging state of these two groups alloys are analyzed, and their stress rupture properties are tested. The effect of silicon on the diffusion of alloy elements and the interaction effect of carbon and silicon on the microstructure and stress rupture properties of the alloy are analyzed. The mechanism of Si on the precipitation behavior of carbide phase in Ni-Mo-Cr-Fe corrosion resistant alloy is discussed. The results show that silicon can promote the diffusion of carbide forming elements and the formation of carbide. The precipitation behavior of the secondary phase is the result of the interaction effect of silicon and carbon, and is related to the thermal history of the alloy. Combined with the characteristic of primary carbides, it is confirmed that the precipitation of M12C type secondary carbide is caused by the relative lack of carbon element and the relative enrichment of carbide forming elements such as molybdenum. The stress rupture properties of two silicon-containing alloys with different carbon contents in solution and aging state are tested. The stress rupture life of low carbon alloy is lower compared with high carbon alloy at solution state, but after aging treatment, the stress rupture life of low carbon alloy is significantly improved, and higher than that of high carbon alloy. The main aim of this research is to reveal the influence mechanism of silicon on carbide phase precipitation of a Ni-Mo-Cr-Fe based corrosion-resistant superalloy, which provides theoretical basis and reference for later alloy design and engineering application.

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Effect of silicon on microstructure and stress rupture properties of a corrosion resistant Ni-based superalloy during long term thermal exposure

Cited by 24 publications

References 21 publications

Carbides Evolution in a Ni-16Mo-7Cr Base Superalloy during Long-Term Thermal Exposure

Carbides Evolution in a Ni-16Mo-7Cr Base Superalloy during Long-Term Thermal Exposure

Improvement of Corrosion Resistance of Hastelloy-N Alloy in LiF-NaF-KF Molten Salt by Laser Cladding Pure Metallic Coatings

Influence Mechanism of Silicon on Carbide Phase Precipitation of a Corrosion Resistance Nickel Based Superalloy

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