γ′ coarsening in high volume fraction nickel-base alloys

MacKay, Rebecca A.; Nathal, M. V.

doi:10.1016/0956-7151(90)90171-c

Cited by 133 publications

(63 citation statements)

References 28 publications

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“…For longer times, k reduces to 7.67 9 10 À4 lm 3 /h. These values for k are somewhere higher compared to literature values from MacKay et al [29] where a quaternary Ni-based system Ni-6 wt pct Al-6 wt pct Ta-X wt pct Mo was investigated with k values in the range of 2 to 18 9 10 À5 lm 3 /h at 1255 K (982°C) depending on the occurring lattice mismatch of c and c¢ due to different Mo concentrations. The high value of k for SEBM CMSX-4 can be explained by regarding two aspects.…”

Section: C/c¢ Microstructure and Coarseningmentioning

confidence: 38%

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Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

Ramsperger

Singer

Körner

2016

Metall Mater Trans A

185

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Powder bed-based additive manufacturing (AM) processes are characterized by very hightemperature gradients and solidification rates. These conditions lead to microstructures orders of magnitude smaller than in conventional casting processes. Especially in the field of high performance alloys, like nickel-base superalloys, this opens new opportunities for homogenization and alloy development. Nevertheless, the high susceptibility to cracking of precipitation-hardenable superalloys is a challenge for AM. In this study, electron beam-based AM is used to fabricate samples from gas-atomized pre-alloyed CMSX-4 powder. The influence of the processing strategy on crack formation is investigated. The samples are characterized by optical and SEM microscopy and analyzed by microprobe analysis. Differential scanning calorimetry is used to demonstrate the effect of the fine microstructure on characteristic temperatures. In addition, in situ heat treatment effects are investigated.

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Section: C/c¢ Microstructure and Coarseningmentioning

confidence: 38%

“…As a consequence, faster growth of the precipitates occurs. Afterwards, more or less stationary temperature conditions in the SEBM process are achieved which were much higher than in the experiments of MacKay et al [29] The higher (stationary) temperatures in SEBM result in a higher value for k.…”

Section: C/c¢ Microstructure and Coarseningmentioning

confidence: 54%

Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

Ramsperger

Singer

Körner

2016

Metall Mater Trans A

185

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“…-C,) r r (19) where C, is the equilibrium solute content, and b is correction factor for the case where volume fraction of precipitates is high (19,20). The correction factor b tends to broaden the precipitate size distribution, which is not tracked by the current mean size approximation.…”

Section: Conventionalmentioning

confidence: 99%

“…The driving potential is provided by the reduction of total interfacial energy while conserving the total volume fraction of precipitates. From coarsening theory (18)(19)(20)(21)(22)(23), the general form of precipitate coarsening can be written as:…”

Section: Conventionalmentioning

confidence: 99%

γ' Formation in a Nickel-Base Disk Superalloy

Gabb¹,

Backman²,

Wei³

et al. 2000

Superalloys 2000 (Ninth International Symposium)

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A streamlined,physics-based kinetic model was formulated, calibrated, and validated on a nickel-base superalloy. It was designed to be simplified and streamlined, to speed up calculations and facilitate linkage to finite element modeling thermal codes. The model describes and predicts the formation of y' precipitates during the heat treatment process. Standardized experimental methods were employed to calibrate and initially validate the microstructure model. The model was then validated on an oil-quenched generic disk. Predictions of primary cooling y' size and area fraction agreed well with experimental measurements over a large range of values and cooling rates.

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“…Lattice mis t δ usually represents the degree of constraint elastic strain between coherent γ and γ ′ phases. The authors of numerous studies have reported that the elastic strain due to lattice mis t has strongly affects the kinetics of microstructure degradation and γ ′ morphology [6][7][8][9][10] . For instance, the shape of the γ ′ particles changes from spherical to a cuboidal and a at and narrow channel between γ and γ ′ phases is stabilized.…”

Section: Introductionmentioning

confidence: 99%

Morphology Evolution of γ′ Precipitates during Isothermal Exposure in Wrought Ni-Based Superalloy Inconel X-750

2017

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The morphological evolution of γ ′ precipitates and lattice mis t with isothermal aging were closely investigated in wrought Ni-based superalloy Inconel X-750. The γ ′ morphology dramatically changes in terms of shape, distribution, coalescence and coherency at the γ/γ ′ interface. These processes and their dependence on temperature are summarized as a γ ′ morphology map together with a time-temperature-precipitation (TTP) diagram through quantifying relevant morphological parameters. The lattice mis t was measured by X-ray diffraction and is positive; it decreases from 0.6% at room temperature to 0.1% at the aging temperature. These results suggest that the morphological changes of the γ ′ precipitates are attributable to very low lattice mis t, the interaction of the elastic eld, the volume fraction of the precipitates and incoherence in γ/γ ′ interface.

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γ′ coarsening in high volume fraction nickel-base alloys

Cited by 133 publications

References 28 publications

Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

γ' Formation in a Nickel-Base Disk Superalloy

Morphology Evolution of γ′ Precipitates during Isothermal Exposure in Wrought Ni-Based Superalloy Inconel X-750

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γ′ coarsening in high volume fraction nickel-base alloys

Cited by 133 publications

References 28 publications

Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

&#947;' Formation in a Nickel-Base Disk Superalloy

Morphology Evolution of γ′ Precipitates during Isothermal Exposure in Wrought Ni-Based Superalloy Inconel X-750

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γ' Formation in a Nickel-Base Disk Superalloy