The Dislocation Mechanics of Crystal/Polycrystal Plasticity

Dislocation Plasticity: Overview

An arbitrary deformation of a material can always be described as the sum of a change in volume and a change in shape at constant volume (shear). Assuming constant structure, the change in volume is recovered when the load is removed, since the atoms can simply relax back to their equilibrium sizes. The change in shape, on the other hand, may or may not be recovered, since the atoms can relax i...

Dislocation core effects in plasticity

Unravelling the physics of size-dependent dislocation-mediated plasticity

Size-affected dislocation-mediated plasticity is important in a wide range of materials and technologies. Here we develop a generalized size-dependent dislocation-based model that predicts strength as a function of crystal/grain size and the dislocation density. Three-dimensional (3D) discrete dislocation dynamics (DDD) simulations reveal the existence of a well-defined relationship between str...

Quantum plasticity and dislocation-induced supersolidity

We suggest that below a certain temperature, the free energy for the creation of kinks-antikinks pairs in the dislocation network of solid He becomes negative. The underlying physical mechanism is the related liberation of vacancies which initiate Feynman’s permutation cycles in the bulk. Consequently, dislocations should wander and sweep an increasingly larger volume at low temperatures. This ...

Coupling discrete dislocation dynamics with polycrystal plasticity

Lebensohn et al. [1] recently introduced an alternative description of crystal plasticity based on a fast-Fourier transform (FFT) algorithm. The FFT approach solves for the equilibrium stress and strains under the constraint of strain compatibility for systems with periodic microstructures. As currently developed, the FFT model describes plasticity with a set of elasto-viscoplastic constitutive...