About this Abstract |
| Meeting |
11th International Symposium on Superalloy 718 and Derivatives 2026: Legacy, Innovations, and Future Directions
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| Symposium
|
Superalloy 718 and Derivatives 2026: Legacy, Innovations, and Future Directions
|
| Presentation Title |
Influence of Heat Treatment on Microstructure of Functionally Graded Alloy 718-NiCrAlY Produced by Directed Energy Deposition |
| Author(s) |
Dilipkumar Choudary Ratnala, Fabian Hanning, Shrikant Joshi, Joel Andersson |
| On-Site Speaker (Planned) |
Dilipkumar Choudary Ratnala |
| Abstract Scope |
NiCrAlY alloys are widely used as bond coating materials to improve oxidation performance and high temperature durability of Nickel based superalloys. In conventional coating systems, the sharp interface between the superalloy substrate and the coating often promotes delamination and cracking under cyclic heat conditions. Replacing this sharp interface with a graded interface reduces interfacial stresses, improves bonding, and enhances the coating durability. The Directed Energy Deposition process with Laser Beam and Powder (DED-LB/p) equipped with a dual powder feeder enables a controlled compositional grading and integrates the deposition process of superalloy substrate and NiCrAlY coating. Hence, in this work compositionally graded Alloy 718-NiCrAlY structures were fabricated in 10 wt% steps using DED-LB/p process. The as deposited Alloy 718 rich regions consisted of a γ-Ni matrix with inter-dendritic Nb-rich Laves phases, while NiCrAlY rich regions exhibited a γ-Ni matrix with β-NiAl phase. Since DED processed Alloy 718 lacks γ´and γ´´ strengthening precipitates in the as built condition, post deposition heat treatment is necessary to develop precipitation strengthening while preserving the β-NiAl phase responsible for oxidation protection in NiCrAlY. This study examines the effect of standard Alloy 718 heat treatment on microstructural evolution and hardness distribution across the Alloy 718-NiCrAlY graded structure, with specific emphasis on γ´/ γ´´ phase precipitation, β-phase stability, and the formation of secondary phases at intermediate compositions. |
| Proceedings Inclusion? |
Definite: At-meeting proceedings |