Demystifying the role of sintering additives with “complexion”

The role of additives has long been a theme in sintering science. Recently, it has been discovered that ceramics may contain multiple different grain boundary phases (complexions) that are chemically induced by certain additives. These complexions are useful in explaining a number of anomalous phenomena associated with sintering, such as abnormal grain growth. The current work investigates how transitions between these complexions occur and at which grain boundaries they are most likely to occur. The number of complexion transitions that occur increases linearly with grain size (grain boundary excess concentration), and exponentially with temperature. The results suggest that grain boundary energy and anisotropy are important in predicting which and how many grain boundaries will undergo such a transition.