Structure-phase transformations in the Be-Fe-Be layered system subjected to irradiation and thermal treatment

The methods of Mössbauer spectroscopy at 57Fe nuclei were used to study changes in structure-phase states of the Be-Fe-Be three-layer system subjected to isothermal annealing, irradiation with helium ions of energies up to 40 keV followed by a series of isochronous annealings. Upon the consequent isothermal annealings at 650 °С, the samples represented a layered system. Its bulk was represented by α-Fe(Be) solid solution and near-surface areas at both sides were mainly represented by FeBe2 intermetallic compound. Irradiation of the near-surface layers resulted in their local enrichment with beryllium atoms. The rate of enrichment depended on the dose, and the dose varied from 1×1021 up to 2×1022 ion/m2. Following consequent 2-hour long isochronous annealings at temperatures from 200 to 650 °С resulted in almost complete recovery of the local concentration of the components and the structure in the irradiated near-surface layers.