Mössbauer Study of Invar-Type Iron-Nickel Alloys

Abstract

By means of the Mössbauer effect internal magnetic fields at iron atom in invar-type iron-nickel alloys were measured using fine powdered samples in which the γ→α martensitic transformation can be suppressed. The absorption spectra of 30 and 32% iron-nickel alloys have a marked feature that a paramagnetic absorption line coexists with normal ferromagnetic ones even at liquid nitrogen temperature which is well below the Curie temperature. The internal magnetic field was found to be nearly constant at 330 kOe over the composition range and the sharp decrease of saturation magnetization of alloys around the composition can semiquantitatively be explained when both of intensities of ferromagnetic and paramagnetic lines are taken into consideration.