This paper presents the results pertaining to thermal and magnetic studies of rapidly-cooled samples of the alloy family Fe₆₁Co₁₀B₂₀Y₈Me₁ (where Me = Nb, Zr, W, Mo). The resulting ribbons, or tapes, have amorphous structure. It has been found that the addition of Me elements alters the thermal and magnetic properties. It is noted that the saturation magnetization decreases with increasing number of unpaired electrons on the valence shells. In addition, the value of the coercivity and effective anisotropy have been determined.
In this work, the results of studies concerning the structure of polycrystalline and amorphous alloys are presented. The samples were produced in a single-step production process, using two different production methods, and under a protective argon atmosphere. The quenching speed of the molten alloy was different for each of the production methods. Samples were subjected to analysis using X-ray diffractometry, scanning electron microscopy, and computer tomography. It has been shown that the samples manufactured with a higher cooling rate feature an amorphous structure; On the other hand, the samples obtained using the method with the lower cooling speed consist of crystallites of three crystalline phases with sizes of the order of μm. The amorphous samples exhibited a varied fracture surface as well as an increase in the contribution of pores to their volume, in comparison to the samples obtained at the lower cooling speed.
Amorphous materials contain structural defects, which play a key role in the magnetization process within the condition known as the "approach to ferromagnetic saturation". This paper presents the results of magnetization studies, carried out on bulk Fe₆₁Co₁₀Ti₃Y₆B₂₀ alloy when under the influence of a strong magnetic field. The alloy samples were obtained in the form of a rod 1 mm in diameter, and tested in the as-quenched state and after an isothermal annealing process, at a temperature below the crystallization temperature. It was observed that the heat treatment, carried out below crystallization temperature Tₓ, leads to irreversible structural relaxations, specifically reorganizing the atomic configuration within the volume of the alloy into an amorphous structure.
The aim of this paper was to conduct studies concerning the magnetization of bulk amorphous (Fe_{0.61}Co_{0.10}Zr_{0.025}Hf_{0.025}Ti_{0.02}W_{0.02}B_{0.20})_{97}Y_{3} alloy when subjected to strong magnetic fields: the specific focus of the paper is the area known as the approach to ferromagnetic saturation. The investigated alloy samples were produced using the suction-casting method, resulting in plates of dimensions 10 mm × 5 mm × 0.5 mm and rods of length 20 mm and diameter 1 mm. The structure was studied using X-ray diffractometry. It was found that investigated samples were amorphous in the as-cast state. The magnetization was measured in a strong magnetic field using a vibrating sample magnetometer. On the basis of the obtained results, the type of structural defects having influence on magnetization in high magnetic fields were determined for the bulk metallic glasses manufactured with different cooling rates.
A study has been conducted into the effects of substituting small quantities of alloying elements (tungsten and molybdenum) on the structure and magnetic properties of classical amorphous alloys that are based on the formula: Fe₆₁Co₁₀Y₈Me₁B₂₀. The structure of the resulting alloy samples was examined using X-ray diffraction, Mössbauer spectroscopy, and scanning electron microscopy. Based on the results of these studies, it was found that the obtained alloys were amorphous. Images from the scanning electron microscope were typical for amorphous materials. Cross-sectional images were homogeneous and did not contain "vein- and scale-type" precipitations. Studies examining the magnetic properties of the samples were carried out using a vibrating sample magnetometer. It was found that the alloy featuring the addition of tungsten exhibited a significantly greater saturation of magnetization and a substantially lower coercivity. This resulted from the fact that the atomic radius of tungsten is much larger than that of molybdenum, resulting in increased difference between the atomic constituents of the alloy; This, in turn, improves the glass-forming ability.
This paper features investigations into the influence of small additions of alloying elements on: structure, as well as the temporal and thermal stability of magnetic properties, and the disaccommodation effect, for the following amorphous alloys: Fe₆₁Co₁₀Y₈Me₁B₂₀ (where Me = Nb, W). The structure of the investigated samples has been confirmed by the Mössbauer spectroscopy. The obtained results indicate a strong correlation between the structure and the disaccommodation of the studied alloys. The Mössbauer studies reveal different configurations of atoms in the amorphous alloy samples, and the results indicate various potential barriers between orientations of atom pairs. For this reason, to describe the disaccommodation effect, the distribution of activation energy should be taken into account. The distribution of activation energy has been related to the distribution of relaxation times.
In this paper the investigations of the ordering, microstructure and magnetomechanical properties of the Fe_{80}Ga_{20} alloy and its composites are presented. The composites consisted of the Fe-Ga particles with a size distribution in the range between 20 and 50 μm. These particles were produced by blade-milling of arc-melted alloy. After milling the powders were annealed at 723 K for 2.5, 7.5, and 12.5 h. The epoxy-bonded composites in rectangular shape were made from the as-cast as well as from the annealed powders. The Mössbauer spectroscopy studies revealed that the as-cast alloy is completely disordered. After annealing at 723 K the long range atomic order appeared. It was stated that the best magnetoelastic properties were exhibited by composites made from ferromagnetic particles obtained from the as-cast alloy. The measured saturation magnetostriction was λ_s= 70× 10^{-6} for the bulk alloy and λ_s=100× 10^{-6} for composite.
The aim of this paper were studies of the structure and magnetic properties of the bulk Fe_{60}Co_{10}W_xMo_{2}Y_{8}B_{20-x} (x=0, 1, 2) alloys. Ingots of the alloys were prepared by arc melting of high purity elements in an argon atmosphere. The samples in the form of plates were obtained by a rapid solidification of liquid metal in a copper mold cooled with water. Topography of produced samples were examined using a ZEISS SUPRA 35 high resolution scanning electron microscope. Furthermore, using a vibrating sample magnetometer the magnetization in high magnetic fields was studied. Moreover, from initial magnetization curves the parameters related with the Holstein-Primakoff paraprocess were determined.
This paper presents the results of studies on the magnetic properties of the Fe_{60}Co_{10}Mo_{2}Y_{8}B_{20} alloy. The samples were fabricated in the form of plates by the injection-casting method. The structure of the investigated alloy, in the as-quenched state and after annealing, was verified by using X-ray diffractometry. The magnetization curves as a function of temperature were measured by a force magnetometer. From thermomagnetic curves the Curie temperature of the alloy was determined. As a critical parameter β was chosen to be equal to 0.36 for these calculations, it confirmed that the alloys may be considered as ferromagnetic of the Heisenberg type. Additionally, using a vibrating sample magnetometer the magnetization and coercivity field were studied (in magnetic field up to 2 T).