AbstractThree spinodally strengthened copper alloys were irradiated with fast neutrons to 34 displacements per atom (dpa) at 414°C, 50 dpa at 411°C, and 32 dpa at 529°C in order to assess their suitability for high-temperature service in neutron environments. Density, electrical conductivity, tensile property, and fracture behavior changes were determined with emphasis on the microstructural reasons for the changes observed. These spinodally strengthened alloys were found to exhibit improved properties following irradiation, and they show merit for use in high-temperature neutron environments, although their low initial conductivity may be a limitation. The results are compared to those of high-purity, unalloyed copper.