Void swelling and defect cluster formation in reactor-irradiated copper

Copper disks were irradiated at temperatures of 182 to 500deg C with moderated fission neutrons under carefully controlled conditions to a damage level of 1.1 to 1.3 dpa at a damage rate of 2x10-7 dpa/s. The lower temperature limit for void formation was found to lie between 182 and 220deg C, with a maximum swelling of about 0.5% at 300 to 350deg C and no swelling at 500deg C. At 182deg C, vacancies produced stacking fault tetrahedra instead of voids. (orig.)