On the peculiar deformation mechanism of ion-induced texture rotation in thin films

Ion-beam irradiation is conventionally used to tune the electronic properties of semiconductors or as a "surrogate" for the study of radiation damage. Recently, it has also been employed for microstructure engineering, namely non-selective and selective grain growth. An even more interesting phenomenon is ion-induced crystal or texture rotation in thin metallic films. This couples an extensive crystal rotation with no significant modification of the grain/film morphology. The present work concentrates on the study of microstructural mechanisms of the phenomenon. A combination of in situ transmission electron microscopy irradiation experiments and finite element simulations reveals that the effect stems from a directional motion of gliding dislocations that is driven by the anisotropic stress field induced in the material surrounding the ion track. The hindrance of dislocation glide at the grain boundaries forces the crystal to relax through a crystal rotation