Transmission electron microscopy (TEM), Auger electron spectroscopy (A
ES) and scanning electron microscopy (SEM) were used for the study of
microstructure changes during creep of alumina in the temperature rang
e of 1150-1300 degrees C. TEM revealed a presence of Si and Ca impurit
ies in the intergranular phase between the Al2O3 grains. AES identifie
d a very thin layer of secondary phase with Ca content on the fracture
surface of the damaged specimens in the areas where microcrack format
ion between grains caused the failure. SEM revealed a cavity/micro-cra
ck formation between the grains during the creep process on the tensil
e surface of the sample stressed in bending mode. Based on the detaile
d analysis, it seems that the main creep controlling mechanism in the
studied material is cavity/microcrack formation influenced by the pres
ence of impurities.