Effect of anorthite liquid on the abnormal grain growth of alumina

A small amount of anorthite (2CaO·Al2O3SiO2) powder was placed on the top-center of the pure Al2O3 powder compact and then sintered at 1600°C. During sintering some grains grew extensively along the radial direction from the liquid source. By considering an atomically smooth solid–liquid interface structure of alumina, grain growth controlled by 2-dimensional (2-D) nucleation was suggested. The elongation has been explained in terms of nucleation advantage of grain-boundary re-entrant edges (GBRE) formed dominantly at non-basal planes.