High temperature Mössbauer effect study ofFe90Zr7B3 nanocrystalline alloy

Abstract

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