Influence of interface energies on solute partitioning mechanisms in doped aluminas

Abstract

The experiments described in this paper have been designed to understand how particular dopants in alumina (Ca, Mg, Si, and Y) affect microstructural development through the energetics of their associated precipitates. Specifically, the role of the interphase boundary energy and precipitation activation energy are considered to be in competition with grain boundary complexion (disorder) transitions for partitioning excess solute. The results reveal a relationship between the relative precipitation activation energy and the temperature at which grain boundary complexion transitions occur. The large differences in activation energy primarily derive from the interphase boundary energy. Precipitates that form lower interphase boundary energies tend to suppress complexion transitions, while systems that contain precipitates with high interphase boundary energies are more susceptible. Based on the findings, a new criterion for additive selection to control complexion transitions and abnormal grain growth is proposed that is based on interfacial energies between the host and precipitate.