Electric-field-assisted sintering of ceramic materials is under considerable attention during recent years. The current research is reviewed with a focus on mechanism research. Research of the mass transfer mechanisms in flash sintering (FS) is under debate during recent years. The research yields three main proposed mechanisms: nucleation due to movement of charged defects, Joule heating runaway, and electrochemical reactions. These are critically presented and discussed. Unlike FS, the mechanism of field-assisted sintering technologies (FAST) of ceramics is well agreed upon. However, recent studies challenge even this perception with new approaches, which are presented here. New technological and methodological developments in both FS and FAST/spark plasma sintering are also presented.

Herein, the mass‐transfer mechanism of flash sintering during the transient stage is examined using an in‐house‐made flash and quench (FQ) system. Visual findings of samples during and after FQ experiments and high‐resolution electron microscopy are given. Many new observations regarding the flash‐sintering nature are presented and discussed. Samples that underwent FQ experiments either show no sign of sintering or local sintering and grain growth due to a hotspot. These findings aid in untying of the two phenomena. Electron microscopy imaging of flash and quenched samples shows atypical microstructures. Such microstructural anomalies include sintering, massive grain growth, and visual findings on the surface. These findings establish flash sintering as a set of phenomena, caused by an abrupt and local increase in temperature (a “flash event”), where only one of which is sintering.

Flash sintering is under research to allow fast, cost‐effective and energy efficient sintering of ceramics. In article, number http://doi.wiley.com/10.1002/adem.202001499, by Yoed Tsur and co‐workers, an in‐house‐made system is constructed for quenching flash sintered samples at mid‐experiment. The system is helpful in further revealing the nature of the phenomenon. The results untie the link between flash and sintering. (Cover design: Nofar Laor)