Flash sintering: A new frontier in defect physics and materials science

Interest in ultrafast sintering has been expanding from different directions that include not only electric and electromagnetic field driven accelerations, but also the influence of heating rates. Among them, the electrical method of flash sintering is most quantitative (and, therefore, most amenable to manufacturing). The electric field, the current density and temperature can be explicitly controlled and measured as a function of time, and related to the sintering behavior and microstructure evolution. In this article, we attempt to explain the greater generality of flash sintering, not just unto itself, but also to heating rate experiments carried out without electrical fields. The rise in electrical conductivity and electroluminescence are the principal features of flash; they are likely to be of general significance in accelerated sintering. Their occurrence in high heating rate experiments, highlighted in this article, is particularly salient, raising new fundamental issues in the science of flash sintering.