Orientation and length scale effects on dislocation structure in highly oriented nanotwinned Cu

Highly oriented nanotwinned Cu has been compressed to 6% strain in directions 90 degrees, 0 degrees and 45 degrees with respect to the twin boundaries of the almost parallel twins. In the 90 degrees and 0 degrees compressed samples Mode I and Mode II dislocations and their interactions with twin boundaries dominate the deformation of twin/matrix (T/M) lamellae with thickness less than 500 nm. In 45 degrees compressed samples, Mode III dislocations, especially partial dislocations moving along the twin boundaries, dominate the deformation of fine T/M lamellae with thickness less than 100 nm, while dislocations from slip Modes I, II and III are identified in T/M lamellae more than 100 nm thick, where these dislocations extensively interact in the T/M lamellae with thicknesses more than 200 nm. Dislocation cells are observed in a twin lamella with a thickness of about 500 nm.