Transmission electron microscopy study of 〈c+a〉 dislocations within [formula omitted] twin in deformed titanium

Abstract

Deformation twins usually play an important role in plastic deformation and undoubtedly influence the mechanical properties of hexagonal close-packed (hcp) materials. Due to the rotated crystallography lattice of the twinned region, the dislocation activity within the twin may differ from that inside the matrix. Thus, understanding the origin and characteristic of these dislocations within the twin would be crucial to microstructural design, processing and application of hcp materials. In the current work, the characteristic of dislocations activated in the grain containing 112¯2 twins in deformed titanium has been investigated by transmission electron microscopy. Multiple type dislocations, including 〈a〉, 〈c〉 and 〈c+a〉 type dislocations, are characterized inside the twin. In contrast, only 〈a〉 type dislocations are detected within the corresponding matrix. In addition, abundant dislocation lines presenting a zigzag feature are found within the twin during deformation. According to these experimental observations, the possible mechanisms responsible for such dislocation features within the twin are proposed and discussed.