PNNL

Abstract

Embedded atom method potentials and atomistic models of coherent (010) interfaces were used to study slip across interfaces in cube on cube oriented CuNi nanolayered materials. (111) disconnections form during slip across CuNi interfaces and become significant barriers to continued deformation. A significant barrier exists for the flat, coherent interface due to the large coherency stresses in the CuNi layers that must be overcome by applied stresses, but once overcome, interface transection occurs readily. A disconnection adds an additional barrier because of a residual dislocation with a Burgers vector equal to the difference of b(sub Cu) and b(sub Ni). This barrier depends on the position of the disconnection relative to the glide plane of the transecting glide dislocation and on the disconnection height. Disconnections cause work hardening that prevents shear band formation during deformation and encourages homogeneous shear processes. Disconnection energies are shown to be relatively small and to depend on the disconnection type and size.