On the role of γ particles within γ′ precipitates on damage accumulation in the P/M nickel-base superalloy N18

Flageolet, Benjamin; Jouiad, Mustapha; Villechaise, Patrick; Méndez, J.

doi:10.1016/j.msea.2005.04.006

Cited by 22 publications

(8 citation statements)

References 5 publications

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“…Deeper characterizations conducted by Merrick [35] on similar particles observed in thermally treated Inconel 738 have enabled to identify those small particles as being γ phase. In more recent studies [36][37][38][39], the presence of similar FCC Cr-enriched particles inside primary γ' precipitates has been reported in the N18 nickel-based superalloy [37,39], and in a nickelcobalt based superalloy [38] when submitted to ageing treatments. The common feature about all those studies that the materials have undergone two thermal treatments: a first one at high (but still sub-solvus) temperature, and a second one at a much lower temperature (usually an ageing treatment).…”

Section: On the Nucleation Of Herx Grainsmentioning

confidence: 54%

Heteroepitaxial recrystallization: A new mechanism discovered in a polycrystalline γ-γ′ nickel based superalloy

Charpagne

Billot

Franchet

et al. 2016

Journal of Alloys and Compounds

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International audienceThe dynamic recrystallization mechanisms and kinetics of a recently developed γ-γ′ nickel based superalloy are studied at different subsolvus temperatures. Special care is paid to the evolution of γ′ particles and their influence on recrystallization phenomena. An original dynamic recrystallization mechanism is highlighted thanks to the combined use of Energy Dispersive Spectrometry and Electron BackScattered Diffraction mapping techniques. This mechanism leads to the formation of large heteroepitaxial pairs, made of a primary precipitate embedded in a recrystallized grain having the same crystallographic orientation. Recrystallization nuclei arise from inverse precipitation of γ phase at the rim of primary γ′ precipitates, prior to deformation. This heteroepitaxial recrystallization mechanism is reported here for the first time. It controls dynamic microstructure evolution at low strains and is then progressively replaced by the conventional discontinuous necklace recrystallization process at higher strains

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Section: On the Nucleation Of Herx Grainsmentioning

confidence: 54%

Heteroepitaxial recrystallization: A new mechanism discovered in a polycrystalline γ-γ′ nickel based superalloy

Charpagne

Billot

Franchet

et al. 2016

Journal of Alloys and Compounds

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“…It is designed for long-term use at 650 o C and limited use at 700 o C. A trade-off between good fatigue crack growth and oxidation resistance as well as excellent creep and strength retention at high temperature was made during alloy design, along with some modification of grain size to optimise this balance, principally adopting sub-solvus heat treatments due to its high γʹ solvus temperatures (~1190°C) [1,[25][26][27][28]. A great deal of research has illustrated that N18 has good phase stability up to 700 o C and possesses high strength and creep resistance associated with a good damage tolerance capability up to 650 o C [1,25].…”

Section: Introductionmentioning

confidence: 99%

Influence of oxidation on fatigue crack initiation and propagation in turbine disc alloy N18

Jiang

Everitt

Gao

et al. 2015

International Journal of Fatigue

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Abstract:Fatigue crack initiation and propagation behaviour in subsolvus heat treated turbine disc alloy N18 has been assessed in air and vacuum at 650 and 725 o C under three-point loading.Fatigue crack initiation processes have been evaluated using single edge U-notch specimens under a 1-1-1-1 trapezoidal loading waveform along with interrupted tests at 650 o C to allow intermittent observations of the notch surface. The results show apparent grain boundary (GB) oxidation can occur under an oxygen partial pressure of 10 -2~1 0 -3 Pa. Cracks mainly initiate from grain boundaries or γ/γʹ interfaces due to the formation and subsequent cracking of Crrich and/or Co-rich oxides, and occasionally initiate from surface pores. Fatigue life in these tests appears to be dominated by this crack initiation process and is significantly reduced by increasing temperature and/or application of an oxidizing environment. Crack growth tests conducted under 1-1-1-1 and 1-20-1-1 loading waveforms indicate that oxidation significantly degrades the crack growth resistance of N18 and is associated with more intergranular fracture surface features. Additional oxidation effects on propagation caused by higher temperature or prolonging dwell time appear limited, whereas a prolonged dwell period seems to instead promote additional creep process, which further enhance crack growth, especially at higher temperature.

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“…There is a very limited number of papers reporting benefit of the kind of hierarchical microstructure by experiments 44,45,[52][53][54][55][56][57][58][59] . Vogel et al 44 showed a 50 HV hardness increase with the presence of FCC precipitates in Ni 78 Al 13 Ti 9 44 L1 2 matrix alloy.…”

Section: Discussionmentioning

confidence: 99%

Hierarchical microstructure strengthening in a single crystal high entropy superalloy

Chen

Chang

Murakami

et al. 2020

Sci Rep

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By contrast, the APT reconstructions in Fig. 2b shows an interesting hierarchical microstructure, in addition to the FCC matrix and the L1 2 phases, there were nano-particles dispersion within the L1 2 phase. These nanoparticles were only present in the HT-2 state, not in the previous HT-1 state. Compositions of each phase in HT-2 state are summarized in Table 1. The calculated partitioning coefficients of Al,

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On the role of γ particles within γ′ precipitates on damage accumulation in the P/M nickel-base superalloy N18

Cited by 22 publications

References 5 publications

Heteroepitaxial recrystallization: A new mechanism discovered in a polycrystalline γ-γ′ nickel based superalloy

Heteroepitaxial recrystallization: A new mechanism discovered in a polycrystalline γ-γ′ nickel based superalloy

Influence of oxidation on fatigue crack initiation and propagation in turbine disc alloy N18

Hierarchical microstructure strengthening in a single crystal high entropy superalloy

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