Observing Dislocations Transported by Twin Boundaries in Al Thin Film: Unusual Pathways for Dislocation–Twin Boundary Interactions
Zongde Kou, Tao Feng, Si Lan, Song Tang, Lixia Yang, Yanqing Yang, Gerhard Wilde
Abstract
Twins are generally regarded as obstacles to dislocations in face-centered cubic metals and can modify individual dislocations by locking them in twin boundaries or obliging them to dissociate. Through in situ tensile experiments on Al thin film in a transmission electron microscope, we report a dynamic process of dislocations being transported by twin lamella via periodic twinning and detwinning at the atomic scale. Following this process, a 60° dislocation first transforms into a sessile step of the twin boundary, then migrates under stress as a step and finally reverts back into a 60° dislocation. Our results reveal a novel evolution route of dislocations by a dislocation-twin interaction where the twins act as transport vehicles rather than as obstacles. The potential implications of this mechanism on toughening are also discussed.