DISLOCATION SWEEPING OF DEFECTS IN NEUTRON-IRRADIATED AND ELECTRON-IRRADIATED NIOBIUM

It is shown that in the case of Nb specimens irradiated with a relatively low fluence of neutrons (approximately 10**2**2 neutrons/m**2) resulting in small defect clusters (approximately 20 nm diameter), the primary mechanism for removal of the clusters by the gliding dislocations was the 'sweeping' of the clusters along with the gliding dislocations. In contrast to the point defects, there appeared to be no transport of the defect clusters (neutron-produced) to the upper or lower specimen surfaces.