Effect of Nb and Cr incorporation on the structural and magnetic properties of rapidly quenched FeCoSiB microwires

Abstract Rapidly quenched microwires with a nominal composition of Fe 39 Co 39 Si 8 B 14 (#A O ), Fe 37 Co 37 Nb 4 Si 8 B 14 (#A N ) and Fe 36 Co 36 Nb 4 Cr 2 Si 8 B 14 (#A NC ) have been investigated. Devitrification of as-quenched microwires showed that crystallization temperatures increased with simultaneous incorporation of Nb and Cr as in #A NC alloy. Addition of these elements also contributed to an increase in activation energy in #A N and #A NC alloys. Nb addition reduced the particle size, which became much finer in the case of the Cr-containing alloy. Although Nb addition did not have much effect on lowering the Curie temperature T C of the amorphous phase, Cr substitution lowered T C to 698 K from high values of 785 K and 787 K observed in the #A O and #A NC alloys, respectively. However, the Cr addition revealed a better Giant magneto-impedance (GMI) response compared to the other alloys. Such improved GMI properties in the Cr-containing alloy are attributed to lower values of the coercivity and magnetostriction in the alloy containing both Nb and Cr.