Creep deformation of 0 degree sapphire

Creep deformation of 0 degree sapphire was studied at 1600 degrees - 1800 degrees at stresses up to 114 MN/m sup 2. Microscopical evidence (dislocation structures observed by TEM and by etch pits) suggested that Nabarro climb was the predominant deformation mechanism. Both the experimental creep rates and stress exponents were in good agreement with those predicted by this model. Although nonbasal dislocations with a 1/3 less than 1101 greater than Burgers vector were present, the good creep resistance of 0 degree sapphire was attributed to the difficulty of activating pyramidal slip.