Influence of Annealing Temperature on Magnetization and Initial Permeability of Fe-Ni Based Amorphous Ribbons

Abstract

Iron-Nickel-Boron (Fe-Ni-B) amorphous ribbons with composition FexNi80-x B20 have been prepared by the melt spinning technique where Ni has been substituted by Fe at constant metalloid Boron. The complex permeability of amorphous ribbon with composition FexNi80-x B20 [x = 20, 30, 40 & 50] are measured as a function of frequency in the range 1 kHz to 13 MHz. The annealing temperature effect on real part of the initial permeability, imaginary part of complex permeability and relative quality factor have been measured for different annealing temperature in the range of room temperature to Curie temperature (Tc). The real part of the initial permeability (µʹ) of all the samples affected by annealing temperature at constant annealing time, is measured at low frequency (1 kHz) and at very low field (H=0.11 A/m). The µʹ increases monotonously with increasing annealing temperature. These effects of annealing lead to the ordering of magnetic atomic pairs, which decreases anisotropy and increase permeability. These effects contribute to an increase of µʹ but at the same time the imaginary component is also influenced, particularly due to eddy currents effects. The magnetic ordering of Fe-Ni-B amorphous ribbons is studied by temperature dependence of initial part of complex permeability at constant frequency. The temperature dependence of ac permeability has been measured by using induction method. The Tc corresponds to temperature at which the sharp fall of permeability occurs. It is notable that addition of Fe has significant effects on enhancement of Tc. Tc of the residual amorphous phase gradually decreases with increase of annealing temperature. A vibrating sample magnetometer (VSM) has been used for measuring magnetization of Fe-Ni-B ribbons of different compositions at room temperature to study for the composition dependence of magnetization. The effect of annealing temperature on magnetization has also been measured using a VSM and observed that saturation magnetization slightly increased in saturation state. The best choice of these parameters depends on the desired characteristics of the material in respect of permeability below than Tc and annealing effects on these properties.