Mössbauer Measurements for a Nanocrystalline Fe44Co44Zr7B4Cu1 Alloy

A two phase microstructure, consisting of nanocrystallites surrounded by an amorphous matrix, was produced by a melt spinning processing route. Alloys of this type have extrinsic properties that are dependent on the relative amounts of the amorphous and nanocrystalline phases. One method for examination of the properties of the nanocrystalline and amorphous phases is by Mössbauer spectroscopy. This paper examines ribbons with the composition of Fe44Co44Zr7B4Cu1, both as-spun and after annealing at 650 C for 1 hour. Three Mössbauer techniques were used to examine these materials, including: transmission measurements, conversion electron Mössbauer spectroscopy, and radio frequency Mössbauer. The transmission spectrum for the annealed HITPERM alloy is composed of two superimposed sextets corresponding to the nanocrystalline FeCo and retained amorphous phases. The rf-Mössbauer results fail to show collapse of the sextet, indicating a large magnetocrystalline anisotropy of the nanocrystalline phase.