Aging of γ′ Precipitates at 750 °C in the Nickel-Based Superalloy AD730TM: A Thermally or Thermo-Mechanically Controlled Process? - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Metals Année : 2020

Aging of γ′ Precipitates at 750 °C in the Nickel-Based Superalloy AD730TM: A Thermally or Thermo-Mechanically Controlled Process?

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Gilbert Hénaff
Anne-Laure Rouffié
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  • IdRef : 180847007
Jean-Michel Franchet
Jonathan Cormier
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  • PersonId : 998670

Résumé

The microstructural stability during aging at 750 °C of the γ/γ′ nickel-based superalloy AD730TM is investigated in this work. Strain-free aging and aging during fatigue tests are conducted, with a focus on the influence of the strain ratio, the maximum applied strain, and the cycle waveform (with or without dwell). Two classical mechanisms of γ′ precipitates aging are identified at 750 °C: the coarsening of small spherical γ′ precipitates via the thermally-activated Ostwald ripening process and the coalescence of at least two precipitates into one. These mechanisms appeared to be concomitant during aging. It has been demonstrated that the coarsening kinetics of γ′ precipitates can be described by a classical Lifshitz-Slyozow-Wagner (LSW) equation. The introduction of a cyclic strain during aging at 750 °C increases the coarsening kinetics by means of changes in the volume diffusion of γ′-forming elements and of constraint misfit effects. More precisely, it is shown that the higher the maximum applied strain and/or the strain rate, the higher the coarsening rates. Finally, dwell-fatigue promotes the activation of the γ′ coalescence at 750 °C.

Dates et versions

hal-02901655 , version 1 (17-07-2020)

Identifiants

Citer

Nicolas Mrozowski, Gilbert Hénaff, Florence Hamon, Anne-Laure Rouffié, Jean-Michel Franchet, et al.. Aging of γ′ Precipitates at 750 °C in the Nickel-Based Superalloy AD730TM: A Thermally or Thermo-Mechanically Controlled Process?. Metals, 2020, 10 (4), pp.426. ⟨10.3390/met10040426⟩. ⟨hal-02901655⟩
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