Magnetic properties and structure of nanocrystalline FINEMET alloys with various iron contents

Abstract

The effect of the composition and annealing temperature on the structure and magnetic properties of soft magnetic nanocrystalline Fe-Cu-Nb-Mo-Si-B alloys has been studied. An increase in the iron content compared to that in the traditional FINEMET alloy is shown to allow one to increase the magnetic induction by 18% at a coercive force of no less than 6 A/m. It has been found that, along with the amorphous phase, rapidly quenched ribbons of alloys enriched in Fe contain crystalline α-Fe-based phase precipitates, the (100) crystallographic directions of which are perpendicular to the ribbon plane. Thermomagnetic analysis and differential scanning calorimetry were used to determine the temperatures of structural and magnetic phase transformations of the alloys with different iron contents. It was found that the separation of amorphous phase into areas of different compositions precedes the precipitation of nano-sized soft magnetic Fe-Si phase grains in the rapidly quenched iron-enriched ribbons.