Interactions between lattice dislocation and Lomer-type low-angle grain boundary in nickel

Abstract

Symmetric tilt Lomer-type low-angle grain boundaries (LLAGBs) are distinct grain boundaries formed by Lomer dislocation locks in face-centered cubic (fcc) metals. To reveal their mechanical behaviors, interactions between lattice dislocation and LLAGB are studied with molecular dynamics simulations. Dislocation reaction and slip transmission depend on the tilt angle of LLAGB, the character of incident dislocation and the particular glide planes inhabiting the incoming slip. For LLAGBs with relatively small tilt-angles, a free slip-transmission zone can be identified where dislocations can be forced to penetrate through the LLAGB without inducing dislocation reaction. Otherwise, the incident slip tends to be trapped, triggering a number of dislocation reactions and leading to indirect slip transmission across the boundary in the reaction zone. Critical strains for dislocation reactions are examined. Raising up the temperature will widen the dislocation reaction zone and the free transmission zone tends to disappear.