Moessbauer study of metastable phase formation in vacuum deposited FeNiCr multilayers due to swift heavy ion irradiation

Conversion electron Moessbauer spectroscopy (CEMS) and X-ray diffraction (XRD) were used to study multilayers, consisting of a few atomic layers of iron, nickel and chromium with a composition 50%Fe-25%Ni-25%Cr, prepared by high vacuum deposition and subsequently irradiated by 246 MeV 86Kr8+ ions at room temperature. Metastable highly disordered microcrystalline ferromagnetic and paramagnetic phases have been detected in the Fe-Ni-Cr multilayers as a result of the swift heavy ion irradiation. These metastable phases never occur with thermally prepared alloys but are similar to those observed previously in the case of Fe-Ni-Cr alloys prepared by other non-equilibrium techniques as electrochemical deposition. The relative amount of these metastable phases increases with the irradiation fluence. It was shown that transformation of metastable phases into the stable ones occurs in high vacuum evaporated and ion beam mixed Fe-Ni-Cr films due to appropriate heat treatment in vacuum