Evidence for Coble creep in the relaxation of surface-compressive stresses in tempered polycrystalline aluminum oxide

Abstract
The kinetics of relaxation of surface-compressive stresses in tempered polycrystalline aluminum oxide were studied. Stress relaxation was observed at temperatures of 775°C and higher. Analysis of the data suggests that the relaxation occurred by Coble creep, which represents the first evidence, although indirect, of the existence of the Coble creep mechanism in ceramics.