Journal of Advanced Materials and Technologies

Journal of Advanced Materials and Technologies

Microstructural Investigation of Silicon‑Modified Aluminide Coatings on IN792 Superalloy via Low‑Activity Out‑of‑Pack Cementation

Document Type : Original Reaearch Article

Authors
Ali Azari Beni 1
saeed rastegari 2
Masoud Hasheminiasari 2
1 PhD Student, School of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran, Tehran, Iran.
2 Associate Professor, School of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran, Tehran, Iran.
10.30501/jamt.2026.577423.1359
Abstract
Silicon-modified aluminide coatings on nickel-based superalloys often suffer from brittleness due to surface-enriched silicide phases. This study introduces a low-activity out-of-pack cementation process conducted at 1050 °C for 240 min under argon to co-deposit Al and Si on the IN792 superalloy, aiming to confine brittle silicides to the inner regions while maintaining a ductile surface. Four powder mixtures with a fixed Al content of 10 wt.% and varying Si contents (0, 5, 10, and 15 wt.%) were used. The simple aluminide coating (sample O, 0% Si) exhibited a dual-layer structure with a total thickness of 45.5 µm, consisting of an outer β-NiAl layer (28.4 µm) and an interdiffusion zone (17.1 µm). The addition of Si reduced the total coating thickness in a nonlinear manner to 42.5 µm (5% Si, sample S3), 44.4 µm (10% Si, sample S2), and 25.6 µm (15% Si, sample S1). The highest Si content (15%) resulted in the greatest reduction, corresponding to an approximately 44% decrease compared with sample O. EDS mapping confirmed that outward Ni diffusion remained the dominant coating growth mechanism in all samples. Importantly, Si enrichment was observed primarily within the interdiffusion zone and at the coating/substrate interface rather than in the outer β-NiAl layer, explaining the absence of silicide peaks in the XRD patterns. This microstructure, consisting of a ductile β-NiAl surface layer over a silicide-rich subsurface region, offers a viable strategy for overcoming brittleness while retaining the oxidation resistance of Si-modified aluminide coatings.
Keywords
IN792 Superalloy
Out of Pack Cementation
Silicon Modified Aluminide Coatings
Low Activity Aluminizing
Subjects
1.      Azari Beni, A., & Rastegari, S. (2025a). Influence of Composition and Process Parameters on Aluminide Coatings Thickness: An Explainable Machine Learning-Assisted Approach. Iranian Journal of Mate`rials Science and Engineering, Research Paper Vol. 22), No. 3(, Pp. 91–103,. https://doi.org/10.22068/ijmse.4057
2.      Azari Beni, A., & Rastegari, S. (2025b). Microstructural investigation of low-activity and high-activity aluminide coatings fabricated by vapor phase aluminizing on IN792 superalloy. Scientific Reports, 15(1), 25284. https://doi.org/10.1038/s41598-025-10549-2
3.      Bakhtiary, O., Sarraf, S., & Soltanieh, M. (2025). Microstructure evaluation of Si-modified aluminide coatings on IN625 deposited by slurry aluminizing process. Surface and Coatings Technology, 495, 131592. https://doi.org/10.1016/j.surfcoat.2024.131592
4.      Behera, A., Sahoo, A. K., & Mahapatra, S. S. (2023). Application of Ni-based superalloy in aero turbine blade: A review. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering. https://doi.org/10.1177/09544089231219104
5.      Beni, A. A., & Rastegari, S. (2026). Mechanism Reversion from Outward to Inward Diffusion in Gas-Phase Aluminizing: The Effect of Powder Composition on Coatings for IN792 Superalloy. Vacuum, 115491. https://doi.org/10.1016/j.vacuum.2026.115491
6.      Dryepondt, S., Pint, B., & Zhang, Y. (2012). Effect of Coating on the Durability at High Temperature of Fe and Ni-based Alloys. CORROSION 2012 (1–8). https://doi.org/10.5006/C2012-01668
7.      Fu, C., Kong, W. K., & Cao, G. H. (2014). Microstructure and oxidation behavior of Al + Si co-deposited coatings on nickel-based superalloys. Surface and Coatings Technology, 258, 347–352. https://doi.org/10.1016/j.surfcoat.2014.09.003
8.      Grégoire, B., Bonnet, G., & Pedraza, F. (2019). Mechanisms of formation of slurry aluminide coatings from Al and Cr microparticles. Surface and Coatings Technology, 359, 323–333. https://doi.org/10.1016/j.surfcoat.2018.11.077
9.      Gudivada, G., & Pandey, A. K. (2023). Recent developments in nickel-based superalloys for gas turbine applications: Review. Journal of Alloys and Compounds, 963, 171128. https://doi.org/10.1016/j.jallcom.2023.171128
10.    Kopec, M. (2024). Recent Advances in the Deposition of Aluminide Coatings on Nickel-Based Superalloys: A Synthetic Review (2019–2023). Coatings, 14(5), 630. https://doi.org/10.3390/coatings14050630
11.    Latief, F. H., Sherif, E. S. M., & Kakehi, K. (2015). Role of Aluminide Coating on Oxidation Resistance of Ni-Based Single Crystal Superalloy at 900°C. International Journal of Electrochemical Science, 10(2), 1873–1882. https://doi.org/10.1016/S1452-3981(23)05118-0
12.    Li, M., Peng, H., & Guo, H. (2025). High-throughput composition screening of Pt-modified aluminide coating for corrosion resistance in molten Na2SO4-NaCl salts at 900°C. Surface and Coatings Technology, 505, 132071. https://doi.org/10.1016/j.surfcoat.2025.132071
13.    Meng, X., Yuwen, P., Shao, W., Qu, W., & Zhou, C. (2018). Cyclic oxidation behaviour of Co/Si co-doped β-NiAl coating on nickel based superalloys. Corrosion Science, 133, 112–119. https://doi.org/10.1016/j.corsci.2018.01.032
14.    Naderi,. M., Farvizi,. M., Shirvani,. K., & Rahimipour, M. R. (2019). Cyclic oxidation behavior of uncoated and aluminum-rich nickel aluminide coated Rene-80 super alloy. Advanced Ceramics Progress. https://doi.org/10.30501/acp.2018.92925
15.    Nouri, S., & Azadeh, M. (2019). Microstructural investigation of the coatings prepared by simultaneous aluminizing and siliconizing process on γ-TiAl. Journal of Mining and Metallurgy, Section B: Metallurgy, 55(2), 217–225. https://doi.org/10.2298/JMMB180814021N
16.    Pauletti, E., & d’Oliveira, A. S. C. M. (2018). Study on the mechanisms of formation of aluminized diffusion coatings on a Ni-base superalloy using different pack aluminization procedures. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 36(4). https://doi.org/10.1116/1.5026272
17.    Pedrizzetti, G., Genova, V., Scrinzi, E., Bottacchiari, R., Conti, M., Paglia, L., & Bartuli, C. (2025). Slurry Aluminizing Mechanisms of Nickel-Based Superalloy and Applicability for the Manufacturing of Platinum-Modified Aluminide Coatings. Coatings, 15(7), 822. https://doi.org/10.3390/coatings15070822
18.    Pint, B. A., Dryepondt, S., Put, A. R. V., & Zhang, Y. (2012). Mechanistic-Based Lifetime Predictions for High-Temperature Alloys and Coatings. JOM, 64(12), 1454–1460. https://doi.org/10.1007/s11837-012-0474-2
19.    Pint, B. A., Haynes, J. A., & Besmann, T. M. (2010). Effect of Hf and Y alloy additions on aluminide coating performance. Surface and Coatings Technology, 204(20), 3287–3293. https://doi.org/10.1016/j.surfcoat.2010.03.040
20.    Rezaee, B., Rastegari, S., & Eyvazjamadi, H. (2021). Formation mechanism of Pt-modified aluminide coating structure by out-of-the-pack aluminizing. Surface Engineering, 37(3), 343–350. https://doi.org/10.1080/02670844.2020.1741212
21.    Rooygari, P., Bakhtiary, O., Alizadeh, Z., Sarraf, S., & Soltanieh, M. (2025). Microstructure Evaluation of IN625 Aluminide Coatings Produced by Reactive Air Aluminizing (RAA) Process: Impact of Temperature and Process Duration. JOM, 77(11), 8368–8384. https://doi.org/10.1007/s11837-025-07600-y
22.    Sarraf, S. H., Soltanieh, M., & Rastegari, S. (2023). Reactive air aluminizing of a nickel-based superalloy (IN738LC): Coating formation mechanism. Surface and Coatings Technology, 456, 129229. https://doi.org/10.1016/j.surfcoat.2023.129229
23.    Sarraf, S., Rastegari, S., & Soltanieh, M. (2024). Deposition of a low-activity type cobalt-modified aluminide coating by slurry aluminizing of a pre-Co-electroplated Ni-based superalloy (IN738LC). Journal of Materials Research and Technology, 30, 1183–1193. https://doi.org/10.1016/j.jmrt.2024.03.132
24.    Sarraf, S., Soltanieh, M., & Rastegari, S. (2025). Isothermal oxidation performance at 1000 °C of two different aluminide coatings deposited by the reactive air aluminizing (RAA) method on a nickel-based superalloy (IN738LC). Journal of Alloys and Compounds, 1010, 178123. https://doi.org/10.1016/j.jallcom.2024.178123
25.    Shirvani, K., & Esmaili,. H. (2016). Interface Thermal Stability Diffusion Aluminide and Silicon Aluminide Coatings with Ni-Based Superalloy GTD- 111. Journal of Advanced Materials and Technologies, 4(3), 33-37., https://doi.org/10.30501/jamt.2637.70305
26.    Shirvani, K., Saremi, M., Nishikata, A., & Tsuru, T. (2002). The role of Silicon on Microstructure and High Temperature Performance of Aluminide Coating on Superalloy In-738LC. MATERIALS TRANSACTIONS, 43(10), 2622–2628. https://doi.org/10.2320/matertrans.43.2622
27.    Taghipour, M., Eslami, A., & Bahrami, A. (2022). High temperature oxidation behavior of aluminide coatings applied on HP-MA heat resistant steel using a gas-phase aluminizing process. Surface and Coatings Technology, 434, 128181. https://doi.org/10.1016/j.surfcoat.2022.128181
28.    Xin, S., Su, B., Li, Q., & Tang, C. (2025). Numerical Study on Chemical Vapor Deposition of Aluminide Coatings. Coatings, 15(8), 974. https://doi.org/10.3390/coatings15080974
29.    Yu, H., Fan, Q., Li, J., Ma, D., Gong, J., & Sun, C. (2023). Effect of Si addition to improve the performance of type II and type I hot corrosion resistance of aluminide coating. Corrosion Science, 212, 110937. https://doi.org/10.1016/j.corsci.2022.110937
30.    Zare Mohazabie, M. S., & Shahriari Nogorani, F. (2019). The addition of zirconium to aluminide coatings: The effect of the aluminide growth mode. Surface and Coatings Technology, 378, 125066. https://doi.org/10.1016/j.surfcoat.2019.125066
31.    Zhang, L., & Zhou, Y. (2023). Oxidation Behavior of Si-Modified Aluminide Coatings on K438 Superalloy Prepared Using a Hybrid Slurry/Pack Cementation Process. Corrosion, 79(1), 111–120. https://doi.org/10.5006/4150
32.    Zhao, Y., Zhou, K., Xin, X., Zeng, X., Guo, X., & Qiao, Y. (2025). Microstructure and oxidation behavior of the aluminized coating on K447A nickel-based superalloy prepared by AlF3-activated pack cementation. Surface and Coatings Technology, 510, 132236. https://doi.org/10.1016/j.surfcoat.2025.132236
33.    Zielińska, M., Zagula-Yavorska, M., Sieniawski, J., & Filip, R. (2013). Microstructure and Oxidation Resistance of an Aluminide Coating on the Nickel Based Superalloy Mar M247 Deposited by the CVD Aluminizing Process. Archives of Metallurgy and Materials, 58(3), 697–701. https://doi.org/10.2478/amm-2013-0057

  • Receive Date 22 February 2026
  • Revise Date 25 May 2026
  • Accept Date 19 June 2026