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
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| Presentation Title |
Dislocation Induced Precipitation of γ’ Phase
during Hot Deformation in VDM Alloy 780 |
| Author(s) |
Fernando Pascual Goce, Masood Hafez Haghighat, Bodo Gehrmann, Marc Bernacki, Madeleine Bignon, Baptiste Flipon |
| On-Site Speaker (Planned) |
Fernando Pascual Goce |
| Abstract Scope |
Nickel-based superalloys are widely used in high-temperature applications due to their excellent mechanical properties in extreme conditions, properties largely attributed to the precipitation of the ordered coherent γ’ phase. VDM Alloy 780 has been developed to extend service temperatures up to 750◦C by increasing the γ’ fraction and microstructure stability through modifications to the chemical composition of Alloy 718. While γ’ precipitation is typically thermally activated, dislocations produced during deformation can act as preferential nucleation sites, significantly influencing the kinetics and morphology of precipitates.
This study investigates the effect of hot deformation, and the associated increase of dislocation density in the microstructure, on γ’ precipitation in VDM Alloy 780. Samples underwent a 15 minutes solution heat treatment to eliminate pre-existing precipitates and stored energy. Subsequently, they were continuously cooled down to subsolvus temperatures, where controlled deformation was applied at varying strain rates and strain levels, followed by water quenching. The resulting microstructures were compared to undeformed reference samples that experienced the same thermal history.
The results reveal a clear deformation-induced precipitation of γ’, with the extent and distribution of precipitation strongly dependent on both strain rate and strain level. At slower strain rates (0.01 s−1), samples exhibit fine precipitation approaching the equilibrium fraction expected at this temperature, whereas no precipitation is observed at higher strain rates (0.1 s−1). |
| Proceedings Inclusion? |
Definite: At-meeting proceedings |