Abstract

Phase constitution and soft magnetic properties of nanocrystalline alloy of composition Fe_72.5Cr₁Nb₃Cu₁Si_13.5B₉ prepared by single roller rapid quenching technique was investigated in this paper. The amorphous nature and the nanocrystal formation of the alloy was determined by X-ray diffraction (XRD) besides the crystallization kinetics was studied by Differential Thermal Analysis (DTA). The annealing temperature was maintained within the range 450oC to 800oC for 30minutes. DTA study reveals the existence of two exothermic peaks one for primary crystallization of   phase and other for secondary crystallization of Fe2B phase. The temperature difference between two crystallization peaks is found to exist ~170oC. This large temperature gap is an indication of the enhancement of stability of  phase against detrimental Fe2B phase. In the optimized annealing condition, the grain size has been obtained in the range of 10-15 nm. The saturation magnetization (Ms) has been observed 128 Am2/kg. In as-prepared condition Curie temperature (Tc) was found 316oC, close compared to the Tc of original FINEMET. Thus, a slight substitution (1 atomic %) of iron (Fe) by chromium (Cr) in original FINEMET enhances the thermo-magnetic stability of the alloy

Keywords

FINEMET, DTA, phase, curie temperature, saturation magnetization