Investigation of Sulphur Nanoclusters in Ageing Ni-S System after Irradiation and Thermal Treatment by Positron Annihilation
D.A. Perminov, A.P. Druzhkov, V.L. Arbuzov and S.E. Danilov
Institute of Metal Physics, Ural Branch of Russian Academy of Science, S. Kovalevskaja Str. 18, 620990 Ekaterinburg, Russian Federation
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The pure Ni and Ni-S ageing systems, thermally aged and also irradiated by 5 MeV electrons at 270 K with subsequent annealing, are studied by means of positron annihilation spectroscopy. The formation of ultrafine S-rich precipitates (clusters) is observed in Ni-S during thermal ageing at about 650 K. It is assumed that these clusters do not contain vacancy-type defects and they are coherent to the Ni matrix. The positrons localize in sulphur clusters that is due to affinity-induced confinement. In irradiated Ni-S system, the mobile vacancy-S atom complexes are formed at post-irradiation annealing above 350 K (stage III). These complexes form: the three-dimensional vacancy clusters (nanovoids) decorated with S atoms. The radiation induced nucleation of S-rich clusters occurs when nanovoids dissociate.

DOI: 10.12693/APhysPolA.125.729
PACS numbers: 81.30.Mh, 61.80.Fe, 64.75.Op