Grain boundary plane distributions in aluminas evolving by normal and abnormal grain growth and displaying different complexions

The grain boundary character distributions of selected doped aluminas were measured from normal and abnormal populations. The relative energies of the A-, C-, and R-planes of undoped alumina were also measured. There is an inverse relationship between the population of grain boundaries and the relative energies of grain boundary planes in undoped alumina. This relationship is found to be qualitative for abnormal grains, whose interfacial anisotropy may be affected by kinetic factors. It is found that the relative grain boundary anisotropy correlates with the temperature dependence of grain boundary complexion transitions in a particular system that is prone to abnormal grain growth. However, there is no direct correlation between the total anisotropy of the grain boundary character distribution and that system's propensity to undergo a particular complexion transition. Therefore, anisotropy will significantly affect the microstructural evolution in systems that are prone to abnormal grain growth, but the magnitude of anisotropy is not a sufficient selection criterion for determining which systems will undergo abnormal grain growth.