arXiv subjects

Felix Schleifer

Publications and source records attributed to Felix Schleifer.

3 recordsLinked to original sources

arXiv2022

Frictionless motion of diffuse interfaces by sharp phase-field modeling

Diffuse interface descriptions offer many advantages for the modeling of microstructure evolution. However, the numerical representation of moving diffuse interfaces on discrete numerical grids involves spurious grid friction, which limits the overall performance of the model in many respects. Interestingly, this intricate and detrimental effect can be overcome in Finite Difference (FD) and Fast Fourier Transformation (FFT) based implementations by employing the so-called Sharp Phase-Field Method (SPFM). The key idea is to restore the discretization induced broken Translational Invariance (TI) in the discrete phase-field equation by using analytic properties of the equilibrium interface profile. We proof that this method can indeed eliminate spurious grid friction in the three dimensional space. Focussing on homogeneous driving forces, we quantitatively evaluate the impact of spurious grid friction on the overall operational performance of different phase-field models. We show that the SPFM provides superior degrees of interface isotropy with respect to energy and kinetics. The latter property enables the frictionless motion of arbitrarily oriented diffuse interfaces on a fixed 3D grid.

cond-mat.mtrl-sci↗

arXiv2022

Sharp phase-field modeling of isotropic solidification with a super efficient spatial resolution

The numerical resolution efficiency of phase-field models is limited by grid friction, grid anisotropy and pinning. The 1D sharp phase-field model eliminates grid friction and pinning by a global restoration of Translational Invariance (TI) in the discretized phase-field equation (Phys. Rev. Lett. 121, 025501, 2018). In 3D global TI restricts the beneficial modeling properties to a finite number of fixed interface orientations. We propose an accurate scheme to restore TI locally in the local interface normal direction. At one-grid-point interface resolutions, the new model captures the formation of isotropic seaweed structures without spurious dendritic selection by grid anisotropy.

cond-mat.mtrl-sci↗

arXiv2020

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

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.

cond-mat.mtrl-sci↗