Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloy

Abstract To improve the oxidation and hot corrosion resistance of components, parts for gas turbine engines made of nickel-based superalloys are often coated with aluminide coatings. Various methods apply these coatings on superalloys. This research examined the vapor phase aluminizing method. The s...

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Main Authors: Ali Azari Beni, Saeed Rastegari
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-10549-2
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author Ali Azari Beni
Saeed Rastegari
author_facet Ali Azari Beni
Saeed Rastegari
author_sort Ali Azari Beni
collection DOAJ
description Abstract To improve the oxidation and hot corrosion resistance of components, parts for gas turbine engines made of nickel-based superalloys are often coated with aluminide coatings. Various methods apply these coatings on superalloys. This research examined the vapor phase aluminizing method. The samples were aluminized through a single-step vapor phase at 1050 °C for a duration of 4 h. This method separates the vapor phase formation chamber from the coating chamber, produces AlxCly vapor in the coating powder input, and transports it to the coating chamber via argon gas to form the aluminide coating. The powder composition was 18 wt% Al, 3 wt% NH4Cl, and 79 wt% Al2O3, and the coating powder inputs considered were 20, 30, 35, and 100 g. After coating, the microstructure and formation of the coating were evaluated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Energy-Dispersive X-ray Spectroscopy (EDS) mapping. The results showed that the thickness of coated samples increased with using more coating powder input from 21.3 μm for 20 g to 68.7 μm for 100 g. The results revealed that powder weights of 20, 30, and 35 g formed low-activity high-temperature (LAHT) aluminide coatings with a double-layer microstructure, with the upper layer free of precipitates, indicating outward diffusion of Ni. The formation of a triple-layer coating for a powder weight of 100 g revealed the presence of precipitates in the upper layer, signifying the inward diffusion of Al. In all coating layers, the matrix phase was β-NiAl, where the outer layer was Al-rich and the interdiffusion zone (IDZ) was Ni-rich.
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spelling doaj-art-ff4ab6e7e5f9473fa25cb170b78e75362025-08-20T03:46:08ZengNature PortfolioScientific Reports2045-23222025-07-0115111310.1038/s41598-025-10549-2Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloyAli Azari Beni0Saeed Rastegari1School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST)School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST)Abstract To improve the oxidation and hot corrosion resistance of components, parts for gas turbine engines made of nickel-based superalloys are often coated with aluminide coatings. Various methods apply these coatings on superalloys. This research examined the vapor phase aluminizing method. The samples were aluminized through a single-step vapor phase at 1050 °C for a duration of 4 h. This method separates the vapor phase formation chamber from the coating chamber, produces AlxCly vapor in the coating powder input, and transports it to the coating chamber via argon gas to form the aluminide coating. The powder composition was 18 wt% Al, 3 wt% NH4Cl, and 79 wt% Al2O3, and the coating powder inputs considered were 20, 30, 35, and 100 g. After coating, the microstructure and formation of the coating were evaluated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Energy-Dispersive X-ray Spectroscopy (EDS) mapping. The results showed that the thickness of coated samples increased with using more coating powder input from 21.3 μm for 20 g to 68.7 μm for 100 g. The results revealed that powder weights of 20, 30, and 35 g formed low-activity high-temperature (LAHT) aluminide coatings with a double-layer microstructure, with the upper layer free of precipitates, indicating outward diffusion of Ni. The formation of a triple-layer coating for a powder weight of 100 g revealed the presence of precipitates in the upper layer, signifying the inward diffusion of Al. In all coating layers, the matrix phase was β-NiAl, where the outer layer was Al-rich and the interdiffusion zone (IDZ) was Ni-rich.https://doi.org/10.1038/s41598-025-10549-2Aluminide coatingsLow-activity typeHigh-activity typeChemical vapour aluminizingSuperalloyIN792
spellingShingle Ali Azari Beni
Saeed Rastegari
Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloy
Scientific Reports
Aluminide coatings
Low-activity type
High-activity type
Chemical vapour aluminizing
Superalloy
IN792
title Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloy
title_full Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloy
title_fullStr Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloy
title_full_unstemmed Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloy
title_short Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloy
title_sort microstructural investigation of low activity and high activity aluminide coatings fabricated by vapor phase aluminizing on in792 superalloy
topic Aluminide coatings
Low-activity type
High-activity type
Chemical vapour aluminizing
Superalloy
IN792
url https://doi.org/10.1038/s41598-025-10549-2
work_keys_str_mv AT aliazaribeni microstructuralinvestigationoflowactivityandhighactivityaluminidecoatingsfabricatedbyvaporphasealuminizingonin792superalloy
AT saeedrastegari microstructuralinvestigationoflowactivityandhighactivityaluminidecoatingsfabricatedbyvaporphasealuminizingonin792superalloy