Primary combination of phase-field and discrete dislocation dynamics methods for investigating athermal plastic deformation in various realistic Ni-base single crystal superalloy microstructures

Abstract

Three-dimensional discrete dislocation dynamics (DDD) simulations in combination with the phase-field method are performed to investigate the influence of different realistic Ni-base single crystal superalloy microstructures with the same volume fraction of γ′ precipitates on plastic deformation at room temperature. The phase-field method is used to generate realistic microstructures as the boundary conditions for DDD simulations in which a constant high uniaxial tensile load is applied along different crystallographic directions. In addition, the lattice mismatch between the γ and γ′ phases is taken into account as a source of internal stresses. Due to the high antiphase boundary energy and the rare formation of superdislocations, precipitate cutting is not observed in the present simulations. Therefore, the plastic deformation is mainly caused by dislocation motion in γ matrix channels. From a comparison of the macroscopic mechanical response and the dislocation evolution for different microstructures in each loading direction, we found that, for a given γ′ phase volume fraction, the optimal microstructure should possess narrow and homogeneous γ matrix channels.

Influence of rafted microstructures on creep in Ni-base single crystal superalloys: a 3D discrete dislocation dynamics study

“…As in our previous study of the primary combination of PF and DDD methods [56], we mesh the γ/γ′ interfaces and import the mesh into the DDD simulation, keeping the same box size. Taking the N-type rafted γ′ morphology in figure 2 as an example, the spaces wrapped by the mesh represent the γ′ precipitates.…”

Numerically efficient microstructure-based calculation of internal stresses in superalloys

“…Since the creep behavior is attributed to the particular microstructure where softer face centered cubic γ matrix is strengthened by stronger cuboidal or spherical L1 2 -ordered g¢ precipitates [9], the crystal plasticity modeling of creep deformation should be also based on this microstructure. Due to the γ/γ′ lattice mismatch and the inhomogeneous deformation in γ matrix and g¢ precipitate during creep, internal stresses are generated, which influences further deformation and rafting of precipitates [10][11][12][13][14]. Although several dislocation-based constitutive models have taken the importance of internal stresses into account [15][16][17], their calculations mainly depend on the common microstructure with narrow γ channels and cubic g¢ precipitate.…”