Phase transition in metallic glasses Fe66Co12Si9B13 and Fe66Ni12Si9b13

Phase transitions were analysed during annealing of amorphous metallic glasses Fe₆₆Co₁₂Si₉B₁₃ and Fe₆₆Ni₁₂Si₉B₁₃. They were measured by means of X-ray diffraction, electrical and Hall resistivity methods. Forming crystalline phases were identified. Those for metallic glasses with cobalt are α-Fe, Fe₃B and Co₂B while those with nickel are α-Fe, Fe₂B, Ni₂B.     

PES study of amorphous alloy Fe40Ni40P20

The electron structure of amorphous Fe₄₀NI₄₀P₂₀ has been investigated before and after annealing by XPS and UPS (HeI, HeII). It is shown that the spectra of UPS were modified obviously by various degree of annealing. Composition and chemical states of the components on the surface of the sample are also presented and the effect of structural ordering on the density of states (DOS) of the valence band is discussed.     

Crystallization of the amorphous Fe45Ni35Si10B10 alloy due to pulse heating

The effect of rapid heating on the stability of amorphous Fe₄₅Ni₃₅Si₁₀B₁₀ is studied in detail by Mössbauer spectroscopy. Structural relaxation as well as formation of crystalline α-Fe and γ(FeNi) is observed, depending on the heating and cooling conditions applied.     

The magnetic anisotropy of cold-rolled and as-quenched amorphous (Fe1−x Ni x )78Si10B12 alloy systems

In order to make clear the origin of magnetic anisotropy of amorphous alloys produced by a single roller quenching method, the composition dependence of the in-plane magnetic anisotropy of cold-rolled and as-quenched amorphous (Fe₁− _x Ni _x )₇₈Si₁₀B₁₂ alloy systems was studied at room temperature. The twofold in-plane magnetic anisotropy constantK _u of cold rolled and as-quenched specimen decreases with increase inx at the Fe-rich side, and increases drastically at aboutx=0.2. Beyondx=0.25,K _u decreases gradually with further increase inx. From this study, it is emphasized that there is a clear correspondence between the atomic ratio of Fe to Ni at which the anomaly in magnetic anisotropy of the amorphous alloy occurs and the position of the fcc/bcc phase boundary in the Fe−Ni metal alloy system.     

Radio-frequency annealing effects in amorphous Fe40Ni40B20

The influence of radio frequency (rf) magnetic fields on the properties of amorphous Fe₄₀Ni₄₀B₂₀ was studied using Mössbauer spectroscopy. The measurements were performed with frequencies of 67 and 53 MHz and rf field intensity in the range of 1 to 12 Oe. The narrowing of the hyperfine spectra due to the rf field and the formation of rf sidebands were observed. The effect of instability and crystallization of the amorphous metal enhanced by the rf field at temperatures much lower than the crystallization temperature was observed.     

Investigation of the magnetic characteristic of amorphous Fe40Ni40B20 and Fe6Co70Ni13Si7B4 foils by a magnetooptical method

Magnetic parameters, the local anisotropy field H_k, the effective field h related to the correlation radius, and the coercive force H_c, are determined for free and contact surfaces by investigating the magnetization curves of amorphous Fe₄₀Ni₄₀B₂₀ and Fe₆Co₇₀Ni₁₃Si₇B₄ foils by a highly-sensitive method of measuring the magnetooptical phase.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 49–52, November, 1989.     

Annealing effects and short-range ordering in the non-magnetostrictive amorphous alloy Co58Ni10Fe5Si11B16

Effects of isothermal and isochronal annealing on the coercive field and the effective magnetic anisotropy in the as-quenched and the stress relieved amorphous alloy Co₅₈Ni₁₀Fe₅Si₁₁B₁₆ were investigated. The mechanisms of the deterioration of soft magnetic properties in non-magnetostrictive amorphous alloys by annealing at low temperatures,T _a <T _c , are discussed. It turned out, that short-range ordering, i.e., topological short-range ordering (TSRO) and chemical short-range ordering (CSRO), caused by annealing lead to changes of the magnetostriction _s , and of the induced magnetic anisotropyK _i . Both effects give rise to an increase of the coercive field. In addition, the kinetics of short-range ordering was studied and from these data, which are closely related to the stability of soft magnetic properties, the activation energy and a preexponential factor was derived:Q _s.r=0.7eV,v ₀=9.6×10³s^–1.     

Effect of crystallization of amorphous Fe5Co75Si4B16 alloy on its optical properties

The optical properties of ferromagnetic Fe₅Co₇₅Si₄B₁₆ alloy in the amorphous state and after temperature treatments have been investigated by spectroscopic ellipsometry in the energy range of 0.073–5.64 eV. It is shown that alloy crystallization changes significantly the frequency dependences of the optical constants and the dielectric functions calculated based on them. The atomic ordering is accompanied by a significant increase in the intensity of the fundamental band of quantum light absorption. The plasma and relaxation frequencies of conduction electrons have been calculated.     

Local structure of Fe70Cr15B15 X-ray amorphous alloy

The local atomic and magnetic structure of Fe₇₀Cr₁₅B₁₅ X-ray amorphous alloy is studied by means of ¹¹B nuclear magnetic resonance (NMR) and ⁵⁷Fe Mössbauer spectroscopy. It is determined that Fe₈₅B₁₅ and Fe₇₀Cr₁₅B₁₅ X-ray amorphous alloys consist of microregions (nanocrystals) with short-range orders of t-Fe₃B and α-Fe phases. It was found out that chromium atoms in the Fe₇₀Cr₁₅B₁₅ X-ray amorphous alloy are evenly distributed in these two nanocrystals, forming t-(Fe,Cr)₃B and α-Fe(Cr) phases.     

Magnetic properties of the amorphous alloy Fe80Er20

Amorphous Fe₈₀Er₂₀ alloys were prepared with the melt spinning technique. The ribbons were investigated by Mössbauer spectroscopy from room temperature to 4.2 K. A phase transition from the paramagnetic to the ferromagnetic phase could be observed. The temperature dependence of the internal magnetic field was measured. The correlations of the hyperfine parameters were determined from the 4.2 K spectrum.     

Effect of silicon additions on the magnetic properties of Nd2Fe12Co2B alloy

The results of magnetic measurements performed on Nd₂Fe_12−xSi_xCo₂B alloys with 0⩽x⩽0.6 are presented. All the compound studied crystallize in the tetragonal Nd₂Fe₁₄B structure. The unit cell volume is found to decrease by introducing Si. With substitution of Fe by Si, the saturation moments decrease, but theanisotropy fields and Curie temperatures are found to increase significantly. For example, in Nd₂Fe_11.5Si_0.5Co₂b, at room temperature, μ_s=28.4μ_B, H_A=80 kOe and T_c=736 K.     

Grain structure of Ni3Fe alloy

The grain structure of aN ₃Fe polycrystal is studied by means of optical metallography taking into account the type of grain boundaries. Grains with random boundaries having special boundaries on the inside are revealed. Grains are classified by the presence and position of special boundaries. The energy of different types of grain boundaries is estimated. Tomsk State University of Architecture and Building. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 34–42, November 1999.     

Magnetooptical investigation of the micromagnetic structure and magnetization processes in Co69Fe4Si12B15 amorphous microwires

Magnetooptical investigation of the micromagnetic structure of Co₆₉Fe₄Si₁₂B₁₅ amorphous microwires 10–50 μm in diameter is carried out. The existence of domains with transverse circumferential magnetization is experimentally demonstrated in the near-surface region of microwires. The dependence of the width of circular domains on the length and diameter of wires is obtained. It is shown that the near-surface micromagnetic structure of amorphous wires is changed under a stretch-induced stress. It is proved that the magnetization reversal of microwires in a longitudinal magnetic field occurs due to the rotation of local magnetization vectors in circular domains.     

Mössbauer studies in amorphous Fe80−x−y Ni x Mn y B12Si8 alloys

Room temperature Mössbauer studies have been carried out on amorphous Fe_80?x?y Ni _x Mn _y B₁₂Si₈ (x=35, 40, 45, 50 and 0≤y≤1). Thex=40 and 45 samples, showed an increase in the average hyperfine field, wheny increased from 0.0 to 0.2 at% in the former and 0.0 to 0.5 at% in the latter. The hyperfine field decreased fory=1.0. This is similar to the results of the magnetic moment on these samples, published earlier.     

Short-range order, atomic structure, and dynamics of the amorphous alloy Ni80Zr20

The method of molecular dynamics with pair-interaction potentials calculated in terms of pseudopotential theory is used to model the rapid quenching process and to study the atomic structure and lattice dynamics of the alloy Ni₈₀Zr₂₀ in the amorphous state. The total and partial atomic radial distribution functions and the densities of vibrational states are calculated, and the nearest-neighbor interatomic distances and coordination numbers are determined. Fiz. Tverd. Tela (St. Petersburg) 39, 961–963 (June 1997)     

Hyperfine interactions in amorphous and nanocrystalline Fe80Ti7Cu1B12 alloy

⁵⁷Fe Mössbauer spectroscopy is used to elucidate the nature of the hyperfine interactions present in amorphous and nanocrystalline forms of Fe₈₀Ti₇Cu₁B₁₂ alloy. Two mutually independent distributions of hyperfine fields and one sextet of Lorentzian lines are employed to reproduce the broad (atoms in amorphous rest and interface zone) and narrow (ordered) parts of the spectra, respectively. The presented conclusions are derived from three-dimensional mapping of the hyperfine field distributions corresponding to both amorphous and interfacial spectral components. The individual distributions are decomposed into Gaussian components which characterize different types of hyperfine interactions.