Abstract
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.