Recoilless fraction, structural, magnetic and thermal properties of Fe 73.5Cu 1Nb 3Si 13.5B 9 alloy

Abstract

Differential scanning calorimetry, X-ray diffraction and room temperature Mössbauer spectrum measurements of Fe 73.5Cu 1Nb 3Si 13.5B 9 (Finemet) alloy have been carried out in order to study its structural and magnetic properties as a function of annealing temperature. The DSC profile of as-quenched Finemet showed two exothermic peaks at 530 and 702 °C, corresponding to two crystallization processes. The Finemet alloy remains amorphous at 450 °C with one broad peak in XRD pattern and one broad sextet in Mössbauer spectrum. When the Finemet alloy was annealed at 550 °C, only well indexed body-center-cubic phase was detected. After being annealed at 650 and 750 °C, the XRD patterns showed the coexistence of α-Fe(Si) and Fe–B intermetallic phases with the increase in XRD peak intensities, indicating the growth of crystallites and the decomposition of Fe 73.5Cu 1Nb 3Si 13.5B 9 alloy at elevated temperatures. The Mössbauer spectra of annealed Finemet alloy could be fitted with 4 or 5 sextets and one doublet at higher annealing temperatures, revealing the appearance of different crystalline phases corresponding to the different Fe sites above the crystallization temperature. The appearance of the nanocrystalline phases at different annealing temperatures was further confirmed by the recoilless fraction measurements.