Multiscale modeling of dislocation-precipitate interactions in Fe: From molecular dynamics to discrete dislocations

Abstract

The stress-driven motion of dislocations in crystalline solids, and thus the ensuing plastic deformation process, is greatly influenced by the presence or absence of various pointlike defects such as precipitates or solute atoms. These defects act as obstacles for dislocation motion and hence affect the mechanical properties of the material. Here we combine molecular dynamics studies with three-dimensional discrete dislocation dynamics simulations in order to model the interaction between different kinds of precipitates and a 1/2〈111〉{110} edge dislocation in BCC iron. We have implemented immobile spherical precipitates into the ParaDis discrete dislocation dynamics code, with the dislocations interacting with the precipitates via a Gaussian potential, generating a normal force acting on the dislocation segments. The parameters used in the discrete dislocation dynamics simulations for the precipitate potential, the dislocation mobility, shear modulus, and dislocation core energy are obtained from molecular dynamics simulations. We compare the critical stresses needed to unpin the dislocation from the precipitate in molecular dynamics and discrete dislocation dynamics simulations in order to fit the two methods together and discuss the variety of the relevant pinning and depinning mechanisms.

Atomic-scale strengthening mechanism of dislocation-obstacle interaction in silicon carbide particle-reinforced copper matrix nanocomposites

“…The edge dislocation introduced on the <110> slip plane is 12 nm away from the left surface, and the distance between particle surface and dislocation is 12 nm. The continuum displacement field of the perfect edge dislocation [25][26][27][28][29][30] …”

“…Recently, Saroukhani et al [27] predicted the rate at which dislocations bypass obstacles to understand the microscopic features that control the plastic behaviors of multi-component alloys, and showed the strain rate sensitivity of the individual dislocation-obstacle interactions. More recently, using MD simulations and 3D discrete dislocation dynamics simulations, Lehtinen et al [26] studied the different kinds of precipitates interacting with edge dislocation in BCC Fe, and discussed the variety of the relevant pinning/depinning mechanisms during the dislocation bypassing precipitate. Although a large number of recent studies have been performed on the strengthening mechanism of the ductile metal particles in PRMMCs [10][11][12][13][14][15][16][17][18][19][25][26][27][28][29][30], the brittle SiC particles on the mechanical properties of Cu matrix have been reported hardly at nanoscale.…”

“…Many studies [24][25][26][27][28][29][30] have explored the dislocation-particle interactions, which involve the change of dislocation core structure and the phase transformation.…”

Interaction of Edge Dislocations with Graphene Nanosheets in Graphene/Fe Composites

“…Furthermore, the simulated yield or depinning stress of the GNS/Fe composites with respect to the GNS location may also be regarded as a critical stress, which could be used as input parameters for a large-scale model. Similar strategy has been used successfully in [36], where dislocation-precipitate interactions in Fe was studied by multiscale modeling and the parameters used in the discrete dislocation dynamics simulations for the dislocation mobility, shear modulus, and dislocation core energy were obtained from MD simulations.…”

A New Precipitation Hardened Austenitic Stainless Steel Investigated by Electron Microscopy

“…The latter may elucidate the exceptionally high strength of this alloy. As can be seen in Figure 5, a large number of dislocations were pinned via the Orowan mechanism (Lehtinen et al, 2016;Kalandyk et al, 2017), forming the main movement blocking; this represents the increase in strength. The precipitate size distribution seems to not depend on the lattice mismatch, which confirmed the finding of Tovar et al (2017).…”