On the recovery of the physical and mechanical properties of a CuCrZr alloy subjected to heat treatments simulating the thermal cycle of hot isostatic pressing

Due to their high mechanical strength and thermal conductivity precipitatio n hardened CuCrZr alloys are being considered as potential heat sink materi al for the ITER divertor vertical target. The fabrication of the divertor c omponent involves a joining procedure by hot isostatic pressing (HIP). The impact of this method on the degradation of the physical and mechanical pro perties of the CuCrZr alloy and their possible subsequent recovery by (re-) aging heat treatments have been investigated by hardness measurements, tens ile testing and measurements of thermal diffusivity and electrical resistiv ity. The thermal cycle of hot isostatic pressing has been simulated by solu tion annealing finished by cooling rates between 0.03 and 1.5 K s(-1). The experiments revealed that a successful recovery of the desired mechanical s trength is only achievable if cooling rates of about 1 K s(-1) or higher ca n be realized after HIP. Otherwise the alloy becomes already over-aged duri ng slow cooling after the joining procedure. (C) 2000 Elsevier Science B.V. All rights reserved.