Soft magnetic properties of nanocrystalline Fe73B7Si16Nb3Cu1 alloy after rapid heating under tensile stress

Abstract

Amorphous Fe 73 B 7 Si 16 Nb 3 Cu 1 ribbon was crystallized rapidly by electric current heating under simultaneously applied tensile stress along the ribbon axis. As a result, strong transverse magnetic anisotropy was induced in the ribbon. Dynamic magnetic properties of the ribbons rapidly heated either under the tensile stress or without tensile stress were measured using toroidal cores. Optimal electric current heating regime that provides maximum improvement of the initial magnetic permeability and core loss was determined. Tensile stress increase from 0 to 180 MPa was shown to result in the decrease of the initial magnetic permeability down to 400 and core loss at frequencies from 0.4 to 200 kHz. Comparative analysis of magnetic properties of the cut core (with non-magnetic gap) and the cores heated under tensile stress was carried out. The magnetic properties of the latter cores are advantageous for manufacturing the reactors and linear chokes of switch-mode power supplies.

Resonance Properties and Magnetic Anisotropy of Nanocrystalline Fe73Cu1Nb3Si16B7 Alloy

“…Therefore, the intensities of resonance lines cannot be used to evaluate the volume fractions of the corresponding regions. At the same time, X-ray structural data [18] demonstrate that the nanocrystalline phase, which corresponds to resonance line 2, comprises about 75 vol%. Figure 3 exhibits the angular dependences of the FM resonance fields for the two detected resonance lines 1 and 2 registered in two measurement configurations.…”

“…For metallic magnets, such conditions are satisfied, if the skin-layer depth exceeds the specimen thickness [20]. For specimens manufactured following the procedure described in this work, but subjected to the annealing for a time interval that was three times longer, the specific electrical resistance was equal to 1.16 × 10 −6 Ω m [18]. The skin-layer depth is about 18 m at a frequency of 9.45 GHz in this case.…”

“…The skin-layer depth is about 18 m at a frequency of 9.45 GHz in this case. Since the shorter annealing times lead, as a rule, to the formation of specimens with higher specific resistances [18], the skin layer in the specimens examined in this work should be expected to exceed the specimen thickness (20 m). Therefore, the application of Kittel equations (1) is correct in this case.…”

“…The rapid heating of an amorphous ribbon, which was fabricated from Fe 73 Cu 1 Nb 3 Si 16 B 7 alloy in the course of its isothermal annealing making use of the electric current induces the appearence of a magnetic anisotropy in this ribbon, which is transverse to the current direction [18]. The origin of this phenomenon has been poorly examined.…”