Dislocation interaction with a tilt low‐angle grain boundary in bi‐crystal SrTiO 3

For potentially wider applications of ceramics with dislocation-tuned mechanical and functional properties, it is pertinent to achieve dislocation engineering in polycrystalline ceramics. However, grain boundaries (GBs) in general are effective barriers for dislocation glide and often result in crack formation when plastic deformation in ceramics is attempted at room temperature. To develop strategies for crack suppression, it is critical to understand the fundamental processes for dislocation–GB interaction. For this purpose, we adopt a model system of bi-crystal SrTiO$_3$ with a 4° tilt GB, which consists of an array of edge dislocations. Room-temperature Brinell indentation was used to generate a plastic zone at the mesoscale without crack formation, allowing for direct assessment of GB-dislocation interaction in bulk samples. Together with dislocation etch pits imaging and transmission electron microscopy analysis, we observe dislocation pileup, storage, and transmission across the low-angle tilt GB. Our experimental observations reveal new insight into dislocation–GB interaction at room temperature at the mesoscale.