Effect of neutron irradiation and post-irradiation annealing on microstructure and mechanical properties of OFHC-copper

Specimens of oxygen-free high conductivity (OFHC) copper were irradiated in the DR-3 reactor at Riso at 100 degreesC to doses in the range 0.01-0.3 dpa (NRT). Some of the specimens were tensile tested in the as-irradiated condition at 100 degreesC whereas others were given a post-irradiation annealing treatment at 300 degreesC for 50 h and subsequently tested at 100 degreesC. The microstructure of specimens was characterized in the as-irradiated as well as irradiated and annealed conditions both before and after tensile deformation. While the interstitial loop microstructure coarsens with irradiation dose, no significant changes were observed in the population of stacking fault tetrahedra (SFT). The post-irradiation annealing leads to only a partial recovery and the level of recovery depends on the irradiation dose level. However, the postirradiation annealing eliminates the yield drop and reinstates enough uniform elongation to render the material useful again. These results are discussed in terms of the cascade-induced source hardening (CISH) model. (C) 2001 Elsevier Science B.V. All rights reserved.