Defects in flash-sintered ceramics and their effects on mechanical properties

The effects of electric field and current during flash sintering have resulted in nonequilibrium microstructures that are not typically observed in conventionally sintered ceramics. In this article, we review the recent findings on the unique microstructural characteristics observed in flash-sintered ceramics and their impacts on mechanical properties. Gradient microstructures across flash-sintered samples are frequently observed and have been investigated using a variety of in situ techniques to monitor the dynamic evolutions in real time. Other microstructural characteristics, such as high-density dislocations and stacking faults, and chemical segregations along grain boundaries, have been reported in flash-sintered ceramics. These defects have been observed in several ceramic systems and were shown to enhance the mechanical properties through defect-mediated inelastic deformation mechanisms. In situ studies on the temperature-dependent transition of deformation mechanisms are also highlighted.