Interstitial loops in neutron irradiated molybdenu

The irradiation of zone-refined molybdenum to a dose of 8 × 1017 nvt at 600°c produces a low density of large prismatic dislocation loops. The loops which number 2 × 1013/cm3 have an average diameter of 1100 Å and are shown to be close to pure edge in character with a Burgers vector a/2〈111〉. Diffraction contrast experiments established that the loops are formed by the aggregation of interstitial atoms. An order of magnitude analysis of the behaviour of radiation-induced defects indicates that vacancies are not sufficiently mobile to aggregate into resolvable loops.