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

Conversion electron Mossbauer spectroscopy (CEMS) and X-ray diffraction (XR D) were used to study multilayers, consisting of a few atomic layers of iro n, nickel and chromium with a composition 50%Fe-25%Ni-25%Cr, prepared by hi gh vacuum deposition and subsequently irradiated by 246 MeV Kr-86(8-) ions at room temperature. Metastable highly disordered microcrystalline ferromag netic and paramagnetic phases have been detected in the Fe-Ni-Cr multilayer s as a result of the swift heavy ion irradiation. These metastable phases n ever occur with thermally prepared alloys but are similar to those observed previously in the case of Fe-Ni-Cr alloys prepared by other non-equilibriu m techniques as electrochemical deposition. The relative amount of these me tastable phases increases with the irradiation fluence. It was shown that t ransformation of metastable phases into the stable ones occurs in high vacu um evaporated and ion beam mixed Fe-Ni-Cr films due to appropriate heat tre atment in vacuum. (C) 2001 Elsevier Science B.V. All rights reserved.