Physical mechanisms leading to recrystallized grains free of precipitates after hot forging of a typical γ − γ′ nickel- based superalloy - Archive ouverte HAL
Communication Dans Un Congrès Année : 2023

Physical mechanisms leading to recrystallized grains free of precipitates after hot forging of a typical γ − γ′ nickel- based superalloy

Federico Orlacchio
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Chi-Toan Nguyen
  • Fonction : Auteur
  • PersonId : 1195847
Marc Bernacki

Résumé

Nickel-based polycrystalline γ - γ' superalloys are used for manufacturing the hottest parts of new generation aircraft engines, such as turbine discs. These materials exhibit a trimodal distribution of γ' precipitates. The largest precipitates, referred to as γ' I (primary precipitates), contribute to grain size control via Smith-Zener pinning effect, while finer precipitate populations, referred to as γ' II and γ' III (resp. secondary and tertiary), induce significant strengthening. Within this family of alloys, recrystallization behavior, and thus microstructure evolution, is significantly influenced by the presence of γ' precipitates whose kinetics of evolution are comparable to those of recrystallization. However, the interaction mechanisms between precipitates and recrystallization remain little understood. While deformed grains exhibit a fine and dense distribution of γ' , no precipitates are observed inside recrystallized grains. This work focuses on the reason for the latter being free of fine precipitates. The hypothesis advanced to explain this interaction mechanism is the dissolution of the fine γ' precipitates present on the recrystallization front, caused by Ostwald ripening, and favored by grain boundary diffusion. A campaign of hot thermo-mechanical tests and SEM-EBSD analysis was defined to study the interaction mechanisms between fine γ' precipitates and the recrystallization front, supported by local chemical analysis via ATP and TEM observations.

Domaines

Matériaux
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Dates et versions

hal-04353707 , version 1 (19-12-2023)

Identifiants

  • HAL Id : hal-04353707 , version 1

Citer

Federico Orlacchio, Daniel Pino Muñoz, Madeleine Bignon, Chi-Toan Nguyen, Marc Bernacki, et al.. Physical mechanisms leading to recrystallized grains free of precipitates after hot forging of a typical γ − γ′ nickel- based superalloy. ReX & GG 2023 - 8th Conference on Recrystallization and Grain Growth, May 2023, Copenhagen, Denmark. ⟨hal-04353707⟩
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