The thermal stability of interstitial-type dislocation loops and cavities in single crystals was studied during isochronal and isothermal annealing. The specimens were bombarded with fast neutrons, at 658 and 1023K, up to 249dpa. During isochronal annealing, dislocation loops started to shrink around 1000K and completely disappeared at 1470K; without changing their character. The cavities grew slightly around 1570K and, above this temperature, they shrank with increasing annealing temperature. The recovery stage of point defects was explained in terms of the thermal stability of defect clusters. Vacancy migration began at about 1000K (corresponding to stage-III), whereas vacancy clusters began to dissociate at about 1570K (corresponding to stage-V). The vacancy migration energy was estimated, from the shrinkage of interstitial-type dislocation loops, to be equal to 2.0eV.

Thermal Stability and Kinetics of Defects in Magnesium Aluminate Spinel Irradiated with Fast Neutrons. K.Yasuda, C.Kinoshita, K.Fukuda, F.A.Garner: Journal of Nuclear Materials, 2000, 283-287, 937-41