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The reflection and absorption properties of powdered nanocrystalline FeSiBCuNb (“Finemet”) alloy at microwaves have been presented. To visualize the shielding ability of this material, the complex permittivity and permeability of pulverized Finemet in the frequency range from 0.2 to 10 GHz have been studied. To measure the permittivity and permeability of powdered Finemet, the modification of the Nicolson, Ross, and Weir method was presented. The modification of this method was mainly based on the unwrapping technique of the measured S-parameter phases. The investigation of permittivity and permeability was realized for pure powders. Four groups of powders with different particle sizes below 200 μm have been investigated. To assess the shielding effectiveness of the nanocrystalline Finemet, two attempts were analyzed. The investigation of the reflection loss of material layer with metal sheet attached to the backside as a reflector was investigated. On the other hand, the reflection and absorption factors of 3-mm-thick layer in free space were additionally analyzed. The obtained results show that the pulverized nanocrystalline Finemet alloy with particle size below 25 μm possesses good absorption properties and, for such particles, the absorption factor is significantly higher than the reflection factor.

Iron-based bulk metallic glasses have been known for several attractive properties, such as high mechanical strength and magnetic softness. They also exhibit sensitivity of magnetic properties to stress, which is the result of magnetoelastic coupling. In this paper, these combined features were exploited to build a simple, but effective magnetoelastic force sensor. It was found that when rods made of glassy (Fe,Co,Ni)-Nb-Si-B alloys, used as cores in a transformer, are subjected to compressive stress, voltage on secondary winding changes with the application of force. When proper measurement conditions are met, the dependence of output voltage versus force is nearly linear. Furthermore, rods with 2 mm in diameter are able to withstand forces reaching 8 kN, which gives an opportunity to design small-sized, high-load magnetoelastic force sensors.

FeCo-based soft magnetic alloys of compositions Fe/sub 45/Co/sub 43/Cu/sub 1/B/sub 3.6/Zr/sub 7.4-x/AM/sub x/, where x=3.7 at.% and 7.4 at.%, and the alloying metals (AM) are Nb and Hf and were prepared in the form of amorphous ribbons by a melt-spinning technique. A two-phase microstructure, consisting of /spl alpha/-FeCo nanocrystals and amorphous matrix, was created by partial devitrification of the amorphous alloys during annealing for 1 h at temperatures 500/spl deg/C-600/spl deg/C. The crystallization process of the amorphous alloys was studied using differential scanning calorimetry, X-ray diffractometry, and transmission electron microscopy. The quasi-static hysteresis loop was measured using an inductive method. Partial replacement of zirconium by hafnium improved thermal stability of the amorphous structure and the magnetic properties of the alloys studied. The effect of niobium is opposite. The best magnetic properties were found in the alloy Fe/sub 45/Co/sub 43/Cu/sub 1/B/sub 3.6/Zr/sub 3.7/Hf/sub 3.7/. It was found that the nanocrystallization temperature strongly influences the thermal stability of the magnetic properties of the alloys studied.