Experimental and numerical investigations of the γ″ and γ′ precipitation kinetics in Alloy 718

Drexler, Andreas; Oberwinkler, Bernd; Primig, Sophie; Turk, Christoph; Povoden-Karadeniz, Erwin; Heinemann, A.; Ecker, Werner; Stockinger, Martin

doi:10.1016/j.msea.2018.03.013

Cited by 53 publications

(19 citation statements)

References 32 publications

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“…Inconel 718 (IN718) is a common precipitation-strengthened Ni-based superalloy used for application in high-pressure turbine discs in jet engines [27][28][29][30][31][32][33][34][35]. However, a majority of the published works focused on wrought IN718 alloys with coarse grains [36,37].…”

Section: Introductionmentioning

confidence: 99%

Thermal Stability of Nanocrystalline Gradient Inconel 718 Alloy

et al. 2021

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Gradient structures containing nanograins in the surface layer have been introduced into Inconel 718 (IN718) nickel-based alloy using the surface mechanical grinding treatment technique. The thermal stability of the gradient IN718 alloy was investigated. Annealing studies reveal that nanograins with a grain size smaller than 40 nm exhibited significantly better thermal stability than those with larger grain size. Transmission electron microscopy analyses reveal that the enhanced thermal stability was attributed to the formation of grain boundaries with low energy configurations. This study provides new insight on strategies to improve the thermal stability of nanocrystalline metals.

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Section: Introductionmentioning

confidence: 99%

Thermal Stability of Nanocrystalline Gradient Inconel 718 Alloy

et al. 2021

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“…Alternatively, several attempts have been made to develop modeling-and-simulation techniques which treat the detailed mechanisms of nucleation, growth, and coarsening of the precipitate phases in 718 (as well as related alloys such as 625 and 718Plus). [24][25][26][27][28] These approaches require large amounts of thermodynamic and kinetic input data and often include simplifying assumptions or calibration/tuning methods whose bases need to be justified. Despite such shortcomings, the tools provide great promise for investigating the effect of changes in processing parameters on heat-treatment response, microstructure variability in large forgings, etc.…”

Section: Introductionmentioning

confidence: 99%

In-Situ Determination of Precipitation Kinetics During Heat Treatment of Superalloy 718

Cormier

Gadaud

Czaplicki

et al. 2020

Metall Mater Trans A

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Two in-situ test techniques were used to obtain insight into the isothermal precipitation kinetics of c¢¢ and c¢ in superalloy 718. The first method consisted of measurements of Young's modulus using a dynamic-resonance method (DRM), and the other comprised determination of the evolution of the lattice parameter of the c-matrix phase via neutron diffraction. For both techniques, solution-treated-and-water-quenched samples were heated to a nominal test temperature of 923 K, 953 K, 1013 K, or 1053 K and held for a time of~5 to 50 hours, at the end of which a near-steady condition in terms of an apparently-constant modulus/lattice parameter had been achieved. The observations from each test technique suggested sequential periods of rapid initial increase in volume fraction followed by a gradually-decreasing rate of change. The data were converted to transformed fraction as a function of time and interpreted in terms of phenomenological (JMAK) and mechanistic (nucleation-and-growth) models. From the former approach, Avrami exponents which decreased from approximately unity at the lower two temperatures to~0.5 at the highest temperature, were deduced. The transformed fraction-versus-time behaviors were well replicated using fast-acting numerical simulations based on the mechanistic model. These simulations highlighted the competition between nucleation and growth in determining overall transformation kinetics.

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“…The size of the c¢¢ particle is typically less than 100 nm in diameter and less than 20 nm in thickness after the aging heat treatment, while the volume fraction of c¢¢ phase is less than 15 pct as reported in literature. [17][18][19][20][21][22][23][24][25] In order to utilize the in-situ neutron diffraction technique related to the c¢¢ phase in Ni-base superalloys, an accurate fitting to the c¢¢ peaks is necessary. Therefore, an approach to obtain c¢¢ diffraction peaks with satisfying quality is required.…”

Section: In-situ Neutron/synchrotron Diffraction Techniquesmentioning

confidence: 99%

Using Variant Selection to Facilitate Accurate Fitting of γ″ Peaks in Neutron Diffraction

Zhang

Qin

et al. 2019

Metall Mater Trans A

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c¢¢ diffraction peaks are hard to discern in neutron/X-ray diffraction patterns, hindering studies on the c¢¢-strengthened superalloys using in-situ diffraction. In this study, we propose a variant selection method to increase the intensity of c¢¢ peaks and to facilitate accurate fitting. The specific variants of c¢¢ are controlled by applying a 300 MPa tensile stress during aging at 790°C for 5 hours. The interaction energy between the applied stress and the transformation strain of each c¢¢ variant differs, leading to an increase in the amount of the variants with a greater energy reduction at the expense of other variants. The enhanced variants result in greater c¢¢ peak intensities in neutron diffraction patterns, allowing both the Pawley refinement and single peak fitting to be performed. Lattice parameters of c¢¢ and c phases, and lattice misfit between the two phases and volume fraction of c¢¢ are acquired. The uncertainties associated with the fitting maintain an acceptable level corresponding to 150 microstrains. The proposed variant selection method shows potential for studying the role of c¢¢ phase in Ni-base superalloys.

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Experimental and numerical investigations of the γ″ and γ′ precipitation kinetics in Alloy 718

Cited by 53 publications

References 32 publications

Thermal Stability of Nanocrystalline Gradient Inconel 718 Alloy

Thermal Stability of Nanocrystalline Gradient Inconel 718 Alloy

In-Situ Determination of Precipitation Kinetics During Heat Treatment of Superalloy 718

Using Variant Selection to Facilitate Accurate Fitting of γ″ Peaks in Neutron Diffraction

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