Structural and soft magnetic properties of nanocrystalline (Fe,Co,Ni)-Ta-C films with high thermal stability

Abstract Nanocrystalline (Fe,Co,Ni) 75–85 -Ta 6–9 -C 10–16 films were prepared over the whole Fe-Co-Ni composition range by annealing sputter-deposited amorphous alloys. Good soft magnetic properties have been obtained over a wide Fe-Co-Ni composition range owing to the nanocrystalline effect. In the films with the coercivity less than 60 A/m, the highest saturation magnetization I s was about 1.7 T. The composition dependence of I s and magnetostriction in the films is similar to that of bulk Fe-Co-Ni alloys because the phases of precipitated Fe-Co-Ni base crystallites in the films are almost the same as those in the bulk alloys. In these films, soft magnetic properties are maintained even after annealing at 973 K because the nanocrystalline structure is stabilized by finely dispersed TaC. Further high thermal stability has been achieved for the films considered to have small intrinsic K 1 . Based on the relation between uniaxial anisotropy and permeability, the effect of the intrinsic magnetocrystalline anisotropy or the anisotropy field on the local anisotropy dispersion is qualitively discussed as well.