Large pores promote abnormal grain growth behavior in calcia doped alumina

This work demonstrates that large pores promote abnormal grain growth, a commonly observed but poorly understood behavior. To investigate this phenomenon, calcia doped aluminum oxide is used as a model ceramic because of its known propensity for abnormal grain growth. Controlled porous microstructures are fabricated using polymer microspheres with nominal diameters approximately an order of magnitude larger than the average grain diameters. Electron backscattered diffraction maps indicate that the introduction of large pores (∼3 vol.%) promotes abnormal grain growth, increasing the total abnormal grain area by more than 60 % when sintered at 1600 °C for 4 h in air. The differences between samples with and without large pores provide insight into the initiation of abnormal grain growth, which is needed to predict microstructure evolution in complex systems with such defects.