Diffuse X-ray scattering studies of neutron- and electron-irradiated Ni, Cu and dilute alloys

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Abstract
Pure Ni and Cu, as well as dilute NiSi0.01, NiGe0.01 and CuBe0.001 alloys, have been irradiated at 6 K with either fast neutrons or 3 MeV electrons. Starting from annealing temperatures well below annealing stage III (i.e. T a ≈ 77 K for Cu and T a ≈ 295 K for Ni) the evolution of the defect structures was studied using diffuse X-ray scattering methods. For both types of irradiation of the pure metals, large interstitial and vacancy dislocation loops developed on annealing. The differences between the behaviour of neutron-irradiated Ni and Cu are discussed in terms of the total number of defects surviving spontaneous recombination and the probability of cascade collapse. A dramatic suppression in the growth of the clusters was observed for the NiSi0.01 and NiGe0.01 alloys and complete recovery was consequently observed at lower temperatures. For the neutron-irradiated, more dilute CuBe0.001 alloys, a suppression of cluster growth was observed only after annealing above stage III. These results are discussed within the model for the trapping reactions developed previously to explain the results of electron irradiation of these same Ni alloys.