Mössbauer Effect in Carburized and Hydrogenated fcc Fe-Ni Invar Alloys

Carburized and hydrogenated fcc Fe-Ni Invar alloys were studied by means of 57 Fe Mössbauer spectroscopy. The characteristic weak ferromagnetic part in their spectra disappears by carburization, and, at the same time, a new component with an internal field considerably smaller than that of the main component appears. The former behaviour is compared with a similar effect of hydrogen and discussed on the basis of the electron theory. The spectral analysis reveals that the new component arises from the iron atoms first-neighbouring with carbon atoms. This effect is similar to that found in the bcc Fe-Ni alloys and accounted for along the same line.