Nanoscale stacking fault-assisted room temperature plasticity in flash-sintered TiO2
Ceramic materials have been widely used for structural applications. However, most ceramics have rather limited
plasticity at low temperatures and fracture well before the onset of plastic yielding. The brittle nature of ceramics
arises from the lack of dislocation activity and the need for high stress to nucleate dislocations. Here, we have
investigated the deformability of TiO2 prepared by a flash-sintering technique. Our in situ studies show that the
flash-sintered TiO2 can be compressed to ~10% strain under room temperature without noticeable crack formation.
The room temperature plasticity in flash-sintered TiO2 is attributed to the formation of nanoscale stacking
faults and nanotwins, which may be assisted by the high-density preexisting defects and oxygen vacancies introduced
by the flash-sintering process. Distinct deformation behaviors have been observed in flash-sintered TiO2
deformed at different testing temperatures, ranging from room temperature to 600°C. Potential mechanisms that
may render ductile ceramic materials are discussed.