Abstract
Strengthening in nanoscale metallic multilayers is closely related to the glide dislocation-interface interaction. The interface can be sheared by the stress of the approaching glide dislocation with its core changed. How the concurrent interface shearing and the dislocation core change influence such interaction dominated strength is studied using three dimensional phase field microelasticity modeling and simulation. The simulated results show that when the glide dislocation is close to or away from the interface, the width of its core changes abruptly in accompany with the interface shear zone broadening or shrinking, respectively. A wider interface shear zone is developed on the interface with a lower shear strength, and can trap the glide dislocation at the interface in a lower energy state, and thus leads a stronger barrier to dislocation transmission. The results further show that the continuum model of the dislocation without the core-width change underestimates the interfacial barrier strength especially for the glide dislocation transmission across weak interfaces.
Highlights
Computer modeling and simulation of defects ensemble and their elastic interactions from atomistic scale to continuum scale are important to get insights into mechanism-based strength or plasticity in materials [1,2]
The results further show that the continuum model of the dislocation without the core-width change underestimates the interfacial barrier strength especially for the glide dislocation transmission across weak interfaces
For a bi-material system with the given stacking fault energy (SFE) mismatch characterized by I =1.0, II =0.2, Figure 2 shows the change of the core width of the glide dislocation decreases rapidly during its transmission across the interface from phase II to phase I under the external shear
Summary
Computer modeling and simulation of defects ensemble and their elastic interactions from atomistic scale to continuum scale are important to get insights into mechanism-based strength or plasticity in materials [1,2]. By using the Green function method for anisotropic bimaterials, Chu et al [18] employ dislocation-based interface shear models to systematically discuss the dislocation-interface interaction for possible implementation into large scale dislocation dynamic simulations. These models suggest that the interface shear results in an attractive force to trap the glide dislocation at the interface and leads to a barrier to dislocation transmission. The weaker interface in shear shows a wider glide dislocation core spreading, results in a deeper energy drop at the interface, and produces a larger attractive force and a stronger interfacial barrier strength for slip transmission [25]. In addition different relaxation rate constants in the phase field model could characterize different dislocation mobilities on the glide plane and the interface, the rate competition between the transmission
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