Effects of Core Dimensions and Manufacturing Procedure on Fluxgate Noise

The effect of demagnetizing factor and manufacturing procedure on noise of the fluxgate probes, manufactured from metallic glasses, is presented. The fluxgate probes were either tape-wound, or flat, wet-etched ringcore and race-track geometries. When combining low demagnetizing factor and high enough cross-section of the probe, a minimum in the noise dependence can be found. For 50 mm ringcores, in such minimum the noise value as low as $7 pT_{RMS}$ in 0.1-10 Hz frequency band was achieved, which is very low for an as-cast tape, and has not been reported before

Unusual magnetic anisotropy of Si-poor FeNbCuBSi alloys

If compared to ribbons of standard FeNbCuBSi (13÷16.5 at.% Si) nanocrystalline alloy, different annealing behaviour is displayed if the above alloy contains 10 and less at.% of Si. The most striking difference is observed on samples annealed/nanocrystallized in an atmosphere (e.g. Ar), where the hard direction is aligned along the ribbon's long axis. The particular annealing behaviour of magnetic anisotropy varies with Si contents, with annealing time and yet it differs for vacuum annealing. These peculiarities are studied on a series of Si-poor FeNbCuBSi alloys by magnetic measurements and Mössbauer spectroscopy, consulting DSC and density measurements as well. Some of the abundant problems are discussed in detail in this work. The main idea to explain the behaviour is based on a squeezing-surface effect which results in forming of magnetoelastic as well as of stress induced anisotropy

Influence of V and Cr Substitutions on Magnetic Properties of FeCoNbB Hitperms

FeCoNbB Hitperm, where 4 at% of Fe are substituted by V or Cr show expected reduction of saturation, slightly lowered magnetostriction and slightly higher coercivity. Despite of significantly larger grain caused by Cr, the coercivity does not increase sharply. Detrimental ambient influences at non-vacuum annealing are not appreciably blocked by V or Cr

Effects of Intrinsic Forces in Toroidal Cores Wound of Soft-Magnetic Ribbons

Magnetic anisotropy as shown by hysteresis loops of tape-wound toroidal cores has been inspected as to the specific response of the anisotropy to core-internal forces during and after annealing. The loops of toroids are compared to that of strip samples annealed together in various ambience. The core-internal forces were manipulated by means of different core construction, too. The results show that it is the heterogeneity, which produces the most effective forces. Different annealing-induced ribbon shrinkage makes the cores effectively heterogeneous and governs their magnetic response, whereas inherent ribbon heterogeneity affects the core properties, too, and is essential for homogeneous cores

Effect of Surfaces of FeNbCuBSiP Ribbons

Boron was partially substituted by phosphorus (3 at.%) in two Si-poor Fe-Nb-Cu-B-Si Finemets. Mostly non-significant changes were observed after vacuum annealing at 500°C, whereas equivalent Ar annealing resulted in significantly better soft-magnetic properties, which suffer from compressive surfaces stress. Possibly by hampering surface crystallization, the substitution eased the surfaces stress and reduced undesired off-axis anisotrophy at the cost of limiting the useful annealing temperature

Effects of substitution of Mo for Nb on less-common properties of Finemet alloys

Particular properties of Fe–Nb/Mo–Cu–B–Si rapidly quenched ribbons were examined. Apart from minor variation, no significant difference due to the Mo for Nb substitution was observed in alloy density and its annealing-induced changes. The same holds for the anisotropic thermal expansion of as-cast ribbon when annealed and for induced anisotropy when annealed under stress. The Mo-substituted ribbons show only slightly higher crystallinity and lower coercivity if annealed in inert gas ambience than in vacuum. Some diversity in surface to interior heterogeneity of the differently annealed ribbons can still be distinguished. Preserving a minor percentage of Nb together with Mo does not seem substantiated to obtain favorable soft magnetic properties of ribbons annealed in inert gas.Fil: Butvin, P.. Slovak Academy of Sciences; EslovaquiaFil: Butvinová, B.. Slovak Academy of Sciences; EslovaquiaFil: Silveyra, Josefina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería; Argentina; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Chromčíková, M.. Slovak Academy of Sciences; EslovaquiaFil: Janičkovič, D.. Slovak Academy of Sciences; EslovaquiaFil: Sitek, J.. Slovak University of Technology; EslovaquiaFil: Švec, P.. Slovak Academy of Sciences; EslovaquiaFil: Vlasák, G.. Slovak Academy of Sciences; Eslovaqui

Accents in Modern High Saturation Nanocrystalline Fe-Rich Alloys

Post processing limits for iron-rich Fe-Cu-Si-B-P high-induction rapidly-quenched ribbons have been tested. 530°C/20 min is already too much, formed borides being the essential culprit of magnetic properties deterioration. Unlike standard Si-poor Fe-Nb-Cu-B-Si Finemets, these alloys annealed even in "technical" Ar below the upper limit do not create significant squeezing surfaces