The effect of neutron spectrum on the mechanical and physical properties of pure copper and copper alloys

The electrical resistivity and tensile properties of copper and oxide dispersion strengthened (DS) copper alloys have been measured before and after fission neutron irradiation to damage levels of 0.5 to 5 displacements per atom (dpa) at ∼ 100 to 400°C. Some of the specimens were irradiated inside a 1.5 mm Cd shroud in order to reduce the thermal neutron flux. The electrical resistivity data could be separated into two components, a solid transmutation component Δρ tr which was proportional to thermal neutron fluence and a radiation defect component Δρ rd which was independent of displacement dose. The saturation value for Δρ rd was ∼ 1.2 nΩ m for pure copper and ∼ 1.6 nΩ m for the DS copper alloys irradiated at 100°C in positions with a fast-to-thermal neutron flux ratio of 5. Considerable radiation hardening was observed in all specimens at irradiation temperatures below 200°C. The yield strength was relatively insensitive to neutron spectrum in specimens strengthened by dispersoids or cold-working.