Segregation and Phase Transformations Along Superlattice Intrinsic Stacking Faults in Ni-Based Superalloys

Smith, Timothy M.; Esser, Bryan D.; Good, Brian S.; Hooshmand, Mohammad S.; Viswanathan, G.B.; Rae, C.M.F.; Ghazisaeidi, Maryam; McComb, David W.; Mills, Michael J.

doi:10.1007/s11661-018-4701-5

Cited by 60 publications

(16 citation statements)

References 41 publications

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“…The scan crosses twin boundaries in both phases without distinct peaks at the interface. Previous observations of segregation of cobalt and chromium at stacking faults and microtwins were observed within γ' precipitates by high resolution TEM [39]. Similarly, the formation of η phase during creep was detected in γ' particles but not the γ matrix [40].…”

Section: Chemical Effects: Segregation and Phase Formationmentioning

confidence: 55%

Deformation twinning during high temperature compression tests of the Ni-base superalloy ATI 718Plus®

2022

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This study discusses the deformation mechanisms active during high temperature compression tests of the Ni-base superalloy ATI 718Plus R . Deformation twins were observed in deformed grains across a range of temperatures and strain rates by use of transmission electron microscopes (TEM). Even at strain rates as low as 0.01 s −1 and temperatures up to 1025 • C the microstructure contained of grains which deformed by deformation twinning. It was concluded that the low stacking fault energy of the alloy, which was measured to be 15mJm −2 caused the formation of the deformation twins. In addition, several examples of the early stages of twin formation were captured. The twinning partials were in most cases emitted from grain boundaries. In a second instance cross-slip events from a Frank-Read source lead to the formation of partials which formed stacking faults.

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Section: Chemical Effects: Segregation and Phase Formationmentioning

confidence: 55%

Deformation twinning during high temperature compression tests of the Ni-base superalloy ATI 718Plus®

2022

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“…Additionally, it is known that segregation of solutes to planar faults influences the defect energies and their formation process significantly [26,[29][30][31][32]. Furthermore, local diffusive reordering processes occur and defect arrangements can be changed driven by an energy reduction [30,[33][34][35]. Another mechanism to form SISFs by climb of Frank partial dislocations was recently reported by Lenz et al [26].…”

Section: Introductionmentioning

confidence: 93%

“…Stacking faults are formed due to a thermally activated reaction of a/2<110>{111} dislocations, which results in a leading partial dislocation of a/3<112> type creating a superlattice intrinsic stacking fault (SISF) and a trailing partial dislocation of a/6<112> type that remains at the / interface. Additionally, it is known that segregation of solutes to planar faults influences the defect energies and their formation process significantly [26,[29][30][31][32]. Furthermore, local diffusive reordering processes occur and defect arrangements can be changed driven by an energy reduction [30,[33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Understanding creep of a single-crystalline Co-Al-W-Ta superalloy by studying the deformation mechanism, segregation tendency and stacking fault energy

et al. 2021

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A systematic study of the compression creep properties of a single-crystalline Co-base superalloy (Co-9Al-7.5W-2Ta) was conducted at 950 °C, 975 °C and 1000 °C to reveal the influence of temperature and the resulting diffusion velocity of solutes like Al, W and Ta on the deformation mechanisms. Two creep rate minima are observed at all temperatures indicating that the deformation mechanisms causing these minima are quite similar. Atomprobe tomography analysis reveals elemental segregation to stacking faults, which had formed in the  phase during creep. Density-functional-theory calculations indicate segregation of W and Ta to the stacking fault and an associated considerable reduction of the stacking fault

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“…The intermetallic γ phase was enriched in elements characterised by the k i γ factor above 1, namely Ta, Ti, Al and Hf, for which mean k i γ strongly exceeded unity, being 3.64-8.09. Alloying elements in the γ phase alter the formation energies of antiphase boundaries, superlattice intrinsic stacking faults and complex stacking faults, and may also directly influence the strength and plasticity of the γ phase [37,38]. The main alloying elements in the γ' precipitates were Al, Hf, Ta, and Ti.…”

Section: Characterisation Of γ and γ' Phases Structure In The Initial Conditionmentioning

confidence: 99%

Characterization of γ′ Precipitates in Cast Ni-Based Superalloy and Their Behaviour at High-Homologous Temperatures Studied by TEM and in Situ XRD

et al. 2020

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In situ X-ray diffraction and transmission electron microscopy has been used to investigate René 108 Ni-based superalloy after short-term annealing at high-homologous temperatures. Current work is focused on characterisation of γ′ precipitates, their volume fraction, evolution of the lattice parameter of γ and γ′ phases and misfit parameter of γ′ in the matrix. Material in the initial condition is characterised by a high-volume fraction (over 63%) of γ′ precipitates. Irregular distribution of alloying elements was observed. Matrix channels were strongly enriched in Cr, Co, W and Mo, whereas precipitates contain large amount of Al, Ti, Ta and Hf. Exposure to high-homologous temperatures in the range 1100–1250 °C led to the dissolution of the precipitates, which influenced the change of lattice parameter of both γ and γ′ phases. The lattice parameter of the matrix continuously grew during holding at high temperatures, which had a dominant influence on the more negative misfit coefficient.

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Segregation and Phase Transformations Along Superlattice Intrinsic Stacking Faults in Ni-Based Superalloys

Cited by 60 publications

References 41 publications

Deformation twinning during high temperature compression tests of the Ni-base superalloy ATI 718Plus®

Deformation twinning during high temperature compression tests of the Ni-base superalloy ATI 718Plus®

Understanding creep of a single-crystalline Co-Al-W-Ta superalloy by studying the deformation mechanism, segregation tendency and stacking fault energy

Characterization of γ′ Precipitates in Cast Ni-Based Superalloy and Their Behaviour at High-Homologous Temperatures Studied by TEM and in Situ XRD

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