Dislocation structures of Σ3 {112} twin boundaries in face centered cubic metals

High resolution transmission electron microscopy of nanotwinned Cu films revealed Sigma 3 {112} incoherent twin boundaries (ITBs), with a repeatable pattern involving units of three {111} atomic planes. Topological analysis shows that Sigma 3 {112} ITBs adopt two types of atomic structure with differing arrangements of Shockley partial dislocations. Atomistic simulations were performed for Cu and Al. These studies revealed the structure of the two types of ITBs, the formation mechanism and stability of the associated 9R phase, and the influence of stacking fault energies on them. The results suggest that Sigma 3 {112} ITBs may migrate through the collective glide of partial dislocations.