Abstract
Dislocation/stacking fault interactions play an important role in the plastic deformation of metallic nanocrystals and polycrystals. These interactions have been explored in atomistic models, which are limited in scale length by high computational cost. In contrast, multiscale material modeling approaches have the potential to simulate the same systems at a fraction of the computational cost. In this paper, we validate the concurrent atomistic-continuum (CAC) method on the interactions between a lattice screw dislocation and a stacking fault (SF) in three face-centered cubic metallic materials—Ni, Al, and Ag. Two types of SFs are considered: intrinsic SF (ISF) and extrinsic SF (ESF). For the three materials at different strain levels, two screw dislocation/ISF interaction modes (annihilation of the ISF and transmission of the dislocation across the ISF) and three screw dislocation/ESF interaction modes (transformation of the ESF into a three-layer twin, transformation of the ESF into an ISF, and transmission of the dislocation across the ESF) are identified. Our results show that CAC is capable of accurately predicting the dislocation/SF interaction modes with greatly reduced DOFs compared to fully-resolved atomistic simulations.
Highlights
Stacking faults (SFs) are planar defects that are commonly observed in face-centered cubic (FCC)metals during plastic deformation [1]
Results are summarized as follows: 1. Two dislocation/intrinsic SF (ISF) interaction modes are observed in Ni and Ag: annihilation of the ISF and the transmission of the screw dislocation across the ISF
In Al, the ISF is always annihilated by the dislocation when the applied shear strain γzx ≤ 6%; with a higher γzx, the ISF is annihilated even in the absence of the lattice dislocation
Summary
Stacking faults (SFs) are planar defects that are commonly observed in face-centered cubic (FCC)metals during plastic deformation [1]. In nanocrystalline Al with an average grain size smaller than 18 nm, an ISF transecting a grain can be formed when a leading partial dislocation nucleated from grain boundaries and triple junctions transits across the grain without the nucleation of a trailing partial dislocation [2]. Thereafter, another dislocation on an intersecting slip plane may interact with the ISF, altering its stacking sequence [3]. Through a set of molecular dynamics (MD) simulations of screw dislocation/SF interactions in five FCC metals, Wei and Wei [4] identified three reaction modes for the ISF (i.e., transformation into an ESF, annihilation, and direct transmission of the dislocation) and the ESF (i.e., transformation into a three-layer twin, transformation into an ISF, and direct transmission of the dislocation), respectively
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