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Flash events, where high-temperature dynamics such as sintering, superplasticity, and crack healing of ceramics are significantly promoted by electric fields and/or currents, have been attracting scientific and technological interests. In this review, anomalous mechanical responses in 8 mol% yttria-stabilized zirconia flash-processed using an AC electric field are described. The dynamic and quasi-static mechanical properties before and after flash processing were evaluated via sound velocity and nanoindentation measurements to characterize the mechanical responses attributed to flash-induced defects. Rate-dependent elastic softening (i.e., the slower the loading rate, the lower the indentation modulus) was observed in the quasi-static range after flash processing, while a negligible change was confirmed in the dynamic elastic behaviors even after flash. Such anomalous mechanical responses in the flash-processed sample are characterized as anelasticity (i.e., viscoelasticity or pseudoelasticity in other terms), which can be attributed to stress-induced and thermally activated recoverable motions of point defect dipoles induced via flash processing. This anelastic behavior may be of importance for understanding the nature of flash induced defects which athermally contribute to the enhanced diffusion during flash events. [ABSTRACT FROM AUTHOR]

When the ceramic green compacts are heated with electric fields, the specimen electric current increases steeply at a certain critical furnace temperature. This phenomenon is called a flash event, and along with this phenomenon, sintering process complete immediately. Flash sintering is a new sintering method that uses this flash event. Various kinds of researches have been reported since Raj et al. found the flash sintering. In addition, some new phenomena induced by the application of electric fields have been pointed out, for example, the change in the point defect configuration due to electric fields. Recently, photo luminescence emission has been found, which is closely related to point defects generated by electric fields during flash event. In this report, we would like to summarize the outline of flash sintering method and to review our recent researches. [ABSTRACT FROM AUTHOR]