When do 2-D dislocations form cellular structures?

Simulations of pattern formation by edge dislocations in two dimensions are presented, with the aim of identifying the simplest type of model which spontaneously evolves dislocation cells and walls. The simulation program adds the forces on each dislocation due to all others, including the force due to external stresses, applying periodic boundary conditions. In lieu of using a general force–velocity relationship, only the dislocation with the strongest force acting on it is moved during each step. Dislocation reactions are given special treatment. Two runs are compared: one allowing two-dimensional mobility, i.e. climb as well as glide, and a second allowing only glide but evolving through several cycles of external stress. A quantitative analysis reveals dislocation walls in both cases, but shows that the latter run, where each dislocation is limited to glide along a line, does not exhibit well-defined dislocation cells. Future goals include introducing dislocation sources, and developing continuum-type models capable of mimicking the dynamics observed.