Self-climb of dislocation loops in magnesium oxide

Abstract

Abstract Quantitative measurements were made of self-climb of dislocation loops, b = 1 2 , in magnesium oxide single crystals. The rate of motion of pairs of co-planar loops was studied by repeated observation of the same areas of a thin foil during a series of annealing treatments. Values 60 300±3500 cal/mol for the activation energy for pipe diffusion and (7·5±4·3) × 10−18 cm4/sec for the pre-exponential term D P o a P were obtained. The experiments show that up to about 1250°C self-climb is a primary mechanism by which average loop size increases during annealing of plastically deformed magnesium oxide.