Nanocrystalline Al thin films have been strained in situ in a transmission electron
microscope using two separate nanomechanical techniques involving a push-to-pull device
and a microelectromechanical system (MEMS) device. Deformation-induced grain growth
was observed to occur via stress-assisted grain boundary migration with extensive grain
growth occurring in the necked region, indicating that the increase in local stress drives the
boundary migration. Under applied tensile stresses close to the ultimate tensile strength of …