Finite-element modelling of anisotropic single-crystal superalloy creep deformation based on dislocation densities of individual slip systems

Preuβner, Johannes; Rudnik, Yegor; Völkl, Rainer; Glatzel, Uwe

doi:10.3139/146.101076

Cited by 9 publications

(3 citation statements)

References 11 publications

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“…boundary condition, a homogeneous value for the normal displacements should be imposed, chosen such that is ideally equilibrates the hydrostatic part of the net deformation from the misfitting particle. Such kind of boundary conditions have been used in respective finite-element models of misfit stresses in the γ/γ systems [41][42][43][44].…”

Section: Simulation Of γ Equilibrium Shapesmentioning

confidence: 99%

Phase-field modeling of γ′-precipitate shapes in nickel-base superalloys and their classification by moment invariants

et al. 2019

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We develop a phase-field model for the simulation of precipitate microstructure pattern formation in nickel-base superalloys. The model accounts for the local effects from inhomogeneous and anisotropic elastic deformations, which mainly result from the lattice misfit between the precipitates and matrix phase. Further, in each time-step, we consider the chemical driving force for precipitate ripening to instantaneously equilibrate to a homogeneous value, leading to conserved phase volumes. The model is applied to study the equilibrium shape of a 2D single γ -particle embedded in the γ-matrix with varying lattice misfit and γ/γ interface energies. Further, we apply the method of moment invariants to quantify the resulting equilibrium shapes of precipitates, which turns out to be a size independent characterization of the particle shape. Resulting values for the 2D moment invariants of experimental as well as simulated particle shapes are discussed and compared. Considering ideally spherical particles, we find that large values for the γ/γ -interface width lead to systematic deviations in the resulting moment invariants.

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Section: Simulation Of γ Equilibrium Shapesmentioning

confidence: 99%

Phase-field modeling of γ′-precipitate shapes in nickel-base superalloys and their classification by moment invariants

et al. 2019

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“…The average overall normal displacements at the boundary is used to allow for the volume change, which leads to more realistic total deformation energies. This boundary condition has previously been applied to finite-element modeling of misfit stresses [75][76][77][78] and equilibrium shapes [23] in the γ/γ system. Due to these boundary conditions, all opposing domain boundaries stay parallel yet no spurious elastic energy is introduced through artificial volume conservation.…”

Section: Boundary Conditionsmentioning

confidence: 99%

Phase-field modeling of γ/γ″ microstructure formation in Ni-based superalloys with high γ″ volume fraction

et al. 2020

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The excellent mechanical properties of the Ni-based superalloy IN718 mainly result from coherent γ precipitates. Due to a strongly anisotropic lattice misfit between the matrix and the precipitate phase, the particles exhibit pronounced plate-shaped morphologies. Using a phase-field model, we investigate various influencing factors that determine the equilibrium shapes of γ precipitates, minimizing the sum of the total elastic and interfacial energy. Upon increasing precipitate phase fractions, the model predicts increasingly stronger particle-particle interactions, leading to shapes with significantly increased aspect ratios. Matching the a priori unknown interfacial energy density to fit experimental γ shapes is sensitive to the phase content imposed in the underlying model. Considering vanishing phase content leads to 30 % lower estimates of the interfacial energy density, as compared to estimates based on realistic phase fractions of 12 %. We consider the periodic arrangement of precipitates in different hexagonal and rectangular superstructures, which result from distinct choices of point-symmetric and periodic boundary conditions. Further, non-volume conserving boundary conditions are implemented to compensate for strains due to an anisotropic lattice mismatch between the γ matrix and the γ precipitate. As compared to conventional boundary conditions, this specifically tailored simulation configuration does not conflict with the systems periodicity and provides substantially more realistic total elastic energies at high precipitate volume fractions. The energetically most favorable superstructure is found to be a hexagonal precipitate arrangement.c 2020. The manuscript is made available under the license CC-BY-NC-ND 4.0

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“…Connected with these two distributions, the ′ volume fraction V ′ is another influence parameter. The relationship between the precipitation microstructure of ∕ � Ni-base superalloys and its mechanical properties, such as the yield strength [4][5][6][7][8] or creep resistance [9,10], is topic of many research works. The total influence of the precipitates is split into multiple mechanisms, relating to different dislocation-precipitate interactions.…”

Section: Introductionmentioning

confidence: 99%

3D Minimum Channel Width Distribution in a Ni-Base Superalloy

Müller

Böttger

Schleifer

et al. 2023

Integr Mater Manuf Innov

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The strength of a Ni-base superalloy depends strongly on its microstructure consisting of cuboidal $${\gamma }^{^{\prime}}$$ γ ′ precipitates surrounded by narrow channels of $$\gamma $$ γ matrix. According to the theory of Orowan, a moving dislocation has to crimp through the minimal inter-precipitate spacing to admit the plastic deformation. We present a novel approach to evaluate the matrix channel width distribution of a matrix/$${\gamma }^{^{\prime}}$$ γ ′ microstructure in binary representation. Our method relies on precise determination of the matrix/precipitate interfaces and requires no additional user input. For each matrix channel between two neighboring precipitates, we identify the minimal interface to interface distance vector with its length being the channel width. The performance of this method is demonstrated on the example of the commercial alloy CSMX-4. We show that, in contrast to conventional line sectioning approaches, the approach consistently handles experimental 2D micrographs and 3D phase-field simulation data. The identified distance vectors correlate to the underlying crystal symmetry independent of the image orientation. The obtained channel width distributions compare well between the 2D and 3D data. This is in terms of similar median and $$\sigma $$ σ of a log-normal distribution. The presented method overcomes limitations of the conventional line slicing approaches and provides a versatile tool for automated microstructure characterization.

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Finite-element modelling of anisotropic single-crystal superalloy creep deformation based on dislocation densities of individual slip systems

Cited by 9 publications

References 11 publications

Phase-field modeling of γ′-precipitate shapes in nickel-base superalloys and their classification by moment invariants

Phase-field modeling of γ′-precipitate shapes in nickel-base superalloys and their classification by moment invariants

Phase-field modeling of γ/γ″ microstructure formation in Ni-based superalloys with high γ″ volume fraction

3D Minimum Channel Width Distribution in a Ni-Base Superalloy

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