High temperature Mössbauer effect study of Fe₉₀Zr₇B₃nanocrystalline alloy

Abstract

Fe90Zr7B3 NANOPERM alloy is investigated in as-quenched and nanocrystalline forms by means of high temperature (up to 1040 K) Mössbauer spectroscopy. These studies are aimed at revealing the relationship of microstructure to magnetic properties for57Fe phases and their temperature dependences in NANOPERM-type ternary alloy at temperatures exceeding the onset of the second crystallization. For this purpose the nanocrystalline sample was prepared by annealing an amorphous precursor at 893 K for 1 h providing 54% of bcc α-Fe nanocrystalline grains. At this stage the first crystallization is almost completed. Because of the progress of the crystallization process during the acquisition of Mössbauer spectra beyond the temperature of the first crystallization, the results obtained are discussed for three temperature intervals: below the first crystallization (782 K), between the first and the second crystallization, and above the second crystallization temperature (931 K). Conclusions related to the evolution of the crystalline fraction, interfacial regions and the amorphous residual phase are derived by comparing spectral parameters obtained from the in situ high temperature Mössbauer effect measurements with those from room temperature Mössbauer spectra acquired immediately after each high temperature experiment. The latter revealed structural modifications imposed during Mössbauer spectroscopy at high temperatures, whereas the in situ experiments identify thermally induced dynamic processes.