Microstructure of Cu-Ni alloys neutron irradiated at 210 degrees C and 420degrees C to 14 dpa

Transmission electron microscope (TEM) disks of pure copper and copper cont aining 0.17-10% Ni were neutron irradiated at 210 degreesC and 420 degreesC in Hf-shielded capsules in the High Flux Isotopes Reactor to doses of 13.5 and 14.9 displacements per atom (dpa), respectively. Void swelling was not observed in any of the specimens irradiated at 210 degreesC. Instead, a hi gh density of stacking fault tetrahedra (SFTs) and a moderate density of di slocation loops were observed. There was no evidence for defect cluster pat terning (wall formation) in any of the specimens irradiated at 210 degreesC . The SFT density was independent of Ni content, whereas the loop density w as highest in the alloy containing similar to2% Ni. Pronounced void swellin g was observed in all of the specimens irradiated at 420 degreesC. A void d enuded zone of similar to2 mum width was observed adjacent to grain boundar ies. The void swelling in copper containing, similar to2% Ni showed a prono unced maximum in a 10-mum wide band adjacent to the grain boundary denuded zones. Matrix voids aligned along [1 1 0] directions were observed in Cu-10 %Ni irradiated at 420 degreesC. The occurrence of the peak swelling zone an d the partial ordering of voids are both consistent with the predictions of the recent production bias model which includes 1-D diffusional transport of clusters of self-interstitial atoms. (C) 2000 Elsevier Science B.V. All rights reserved.