Shearing mechanisms of co-precipitates in IN718

Zenk, Christopher H.; Feng, Longsheng; McAllister, Donald; Mills, Michael J.

doi:10.1016/j.actamat.2021.117305

Cited by 19 publications

(2 citation statements)

References 21 publications

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“…For example, the planar fault traversing from the bottom left to the top right of the micrograph shows isolated faulted coprecipitates. Isolated faults have been frequently reported for air-cooled IN718 containing non-compact coprecipitates, deformed under similar conditions [19][20][21][22][23]. Further, across this micrograph, several dislocation loop/debris like features are visible.…”

Section: Discussionsupporting

confidence: 67%

Creep Behavior of Compact γ′-γ″ Coprecipitation Strengthened IN718-Variant Superalloy

Mukopadhyay

Sriram

Zenk

et al. 2021

Metals

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The development of high-temperature heavy-duty turbine disk materials is critical for improving the overall efficiency of combined cycle power plants. An alloy development strategy to this end involves superalloys strengthened by ‘compact’ γ′-γ″ coprecipitates. Compact morphology of coprecipitates consists of a cuboidal γ′ precipitate such that γ″ discs coat its six {001} faces. The present work is an attempt to investigate the microstructure and creep behavior of a fully aged alloy exhibiting compact coprecipitates. We conducted heat treatments, detailed microstructural characterization, and creep testing at 1200 °F (649 °C) on an IN718-variant alloy. Our results indicate that aged IN718-27 samples exhibit a relatively uniform distribution of compact coprecipitates, irrespective of the cooling rate. However, the alloy ruptured at low strains during creep tests at 1200 °F (649 °C). At 100 ksi (689 MPa) load, the alloy fails around 0.1% strain, and 75 ksi (517 MPa) loading causes rupture at 0.3% strain. We also report extensive intergranular failure in all the tested samples, which is attributed to cracking along grain boundary precipitates. The results suggest that while the compact coprecipitates are indeed thermally stable during thermomechanical processing, the microstructure of the alloy needs to be optimized for better creep strength and rupture life.

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Section: Discussionsupporting

confidence: 67%

Creep Behavior of Compact γ′-γ″ Coprecipitation Strengthened IN718-Variant Superalloy

Mukopadhyay

Sriram

Zenk

et al. 2021

Metals

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“…This is in agreement with the experimental results which show composite c 00 =c 0 precipitates in the c matrix at low temperatures. [30] Co also prefers to be at the 001 interface (E 100 seg >0 and E 001 seg <0). However, Co has lower energy when it is in the c matrix [7] and, thus, it will not stay in the c 00 -phase but rather move to the c phase and diffuse away from the interface.…”

Section: Resultsmentioning

confidence: 99%

Effects of Alloying on the Interface Energy of the $$\gamma ''$$-Phase in Nickel-Based Superalloys

Ngo-Dinh

Bäker

2023

Metall Mater Trans A

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Nickel-based superalloys of the 718 type have been extensively used in the production of engine parts which operate at high temperatures. The alloy is strengthened by the precipitation of small $$\gamma ''$$ γ ′ ′ -phase particles with a large lattice distortion in the $$\gamma $$ γ matrix. These $$\gamma ''$$ γ ′ ′ -phase particles, however, may transform to the more thermodynamically stable $$\delta $$ δ -phase. Such transformation might be mitigated by adding other alloying elements. In this work, we used density functional theory calculations at 0 K to study the influence of relevant alloying elements on the interface energy of the $$\gamma ''/\gamma $$ γ ′ ′ / γ coherent interfaces. By replacing an atom either in the $$\gamma ''$$ γ ′ ′ -phase or at the interface and calculating the corresponding interface segregation energy, we assessed the favorable replacement position of each alloying element. Implications of our results on the $$\gamma ''$$ γ ′ ′ -phase growth are also discussed.

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Subcritical Crack Growth of Alloy 718 in Marine Exposure Conditions and Microstructural Modeling

Arcari¹,

Horton²,

Zikry³

et al. 2023

The Minerals, Metals &Amp; Materials Series

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Shearing mechanisms of co-precipitates in IN718

Cited by 19 publications

References 21 publications

Creep Behavior of Compact γ′-γ″ Coprecipitation Strengthened IN718-Variant Superalloy

Creep Behavior of Compact γ′-γ″ Coprecipitation Strengthened IN718-Variant Superalloy

Effects of Alloying on the Interface Energy of the $$\gamma ''$$-Phase in Nickel-Based Superalloys

Subcritical Crack Growth of Alloy 718 in Marine Exposure Conditions and Microstructural Modeling

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