Effect of heat treatments on precipitate microstructure and mechanical properties of a CuCrZr alloy

The precipitate microstructure of prime aged CuCrZr was coarsened by overaging to see if the larger precipitates could prevent the initiation of plastic flow localization in irradiated CuCrZr. A number of tensile and fracture toughness specimens of prime aged CuCrZr alloy were given overaging treatments at 873 K for 1, 2 and 4 h. A subset of these specimens were irradiated with fission neutrons in the BR-2 reactor at Mol (Belgium) at 333 K and 573 K to a dose level of ∼0.3 dpa. Both unirradiated and irradiated tensile specimens were tested at 295 K, 333 K and 573 K. Fracture toughness tests were carried out at 293, 333 and 573 K. Transmission electron microscopy was used to investigate the effects of overaging, subsequent irradiation and the effect of deformation. The results indicate that the overaging treatment of 873 K for 1 h produced a precipitate microstructure that improved the plastic instability, overall ductility and fracture toughness.