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 precipitation hardened CuCrZr alloys are being considered as potential heat sink material for the ITER divertor vertical target. The fabrication of the divertor component involves a joining procedure by hot isostatic pressing (HIP). The impact of this method on the degradation of the physical and mechanical properties of the CuCrZr alloy and their possible subsequent recovery by (re-)aging heat treatments have been investigated by hardness measurements, tensile testing and measurements of thermal diffusivity and electrical resistivity. The thermal cycle of hot isostatic pressing has been simulated by solution 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 strength is only achievable if cooling rates of about 1 K s(-1) or higher can be realized after HIP. Otherwise the alloy becomes already over-aged during slow cooling after the joining procedure. (C) 2000 Elsevier Science B.V. All rights reserved.