High-Temperature Kilocycle Internal Friction in Al2O3 Single Crystals

Abstract
Dislocation damping in Al2O3 single crystals has been measured to 1850°C. Undeformed specimens show no damping greater than δ = 10−5. Deformed specimens have an exponentially rising damping above 1450°C with an activation energy of 100–120 kcal/mole. The damping is amplitude independent at least to 10−5 strain amplitude. Dislocation densities and distributions for the specimens were determined by surface etching.