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The structure evolution and low-field magnetic properties (i.e. the magnetic susceptibility and its disaccommodation) during transformation of the Fe85.4Zr6.8−xNbxB6.8Cu1 (x=0,1) alloys from the amorphous to the nanocrystalline state are investigated. It was stated that at early stages of crystallization, the iron content in the amorphous matrix does not change. However, the interfacial layer is poorer in iron in comparison with the amorphous matrix. The annealing of the amorphous samples below the crystallization temperature leads to the decrease of the hyperfine field due to the invar effect. Moreover, at early stages of crystallization, the samples exhibit “magnetic hardening”. The magnetic susceptibility disaccommodation of the investigated alloys is mainly connected with relaxation processes occurring in the amorphous phase. [Copyright &y& Elsevier]

After annealing alloys below crystallization temperatures, the decrease of the average hyperfine field due to the invar effect is observed. At early stages of crystallization, the iron content in the amorphous matrix is the same as in the as-quenched state. The amorphous samples show broad disaccommodation spectra with activation energies from 0.6 to 0.9 eV. The highest initial magnetic susceptibility was obtained for the nanocrystalline Fe85.4Zr5.8Nb1B6.8Cu1 alloy. However, the best thermal stability of the susceptibility is observed for the Fe85.4Zr6.8B6.8Cu1 alloy. [Copyright &y& Elsevier]

Heat-treated Fe42.7Co42.7Zr6.8−xNbxB6.8Cu1 (x=0,1) alloys were studied. During nanocrystallization of these alloys, the ordered α′-FeCo phase is formed. Moreover, the magnetic susceptibility of the nanocrystalline alloys slightly depends on temperature. Furthermore, the relaxation processes occurring in the amorphous matrix are the main source of the magnetic susceptibility disaccommodation in nanocrystalline alloys. [Copyright &y& Elsevier]

It has been found that the replacement of 50% of Fe atoms by Co atoms in the Fe83Nb3B13Cu1 amorphous alloy enhances the saturation magnetization. The presence of α-FeCo grains in the nanocrystalline Fe41.5Co41.5Nb3B13Cu1 alloy leads to higher magnetic susceptibility and saturation magnetization at elevated temperatures in comparison with the Fe83Nb3B13Cu1 one. [Copyright &y& Elsevier]

Abstract: Using a suction-casting method the bulk amorphous ( or 2, , Nb, Ti) alloys in the shape of rods (1mm diameter), tubes and rings (4 and 8mm outer diameter, respectively) have been obtained. Those alloys show relatively high Curie temperatures (about 500K) and crystallization temperatures (about 860K). Moreover, we have found that those alloys show good soft magnetic properties. [Copyright &y& Elsevier]

Abstract: Microstructure by X-ray diffraction and Mössbauer spectroscopy, and isothermal magnetic entropy changes in the bulk amorphous Fe60Co5Zr8Mo5W2B20 alloy in the as-quenched state and after annealing at 720K for 15min are studied. The as-cast and heat treated alloy is paramagnetic at room temperature. The quadrupole splitting distribution is unimodal after annealing indicating the more homogenous structure in comparison with that for the as-cast alloy. Curie temperature slightly increases after annealing from 265±2K in the as-quenched state to 272±2K and the alloy exhibits the second order magnetic phase transition. The maximum of isothermal magnetic entropy changes appears at the Curie points and is equal to 0.30 and 0.42J/(kg·K) for the alloy in the as-quenched state and after annealing, respectively. In the paramagnetic region the material behaves as a Curie–Weiss paramagnet. [Copyright &y& Elsevier]

Transmission Mössbauer spectra of amorphous Fe86Zr7Nb1Cu1B5, Fe81Zr7Nb1Cu1B10 and Fe81Pt5Zr7Nb1Cu1B5 alloys in the as-quenched state and subjected to the accumulative annealing for 15min in the temperature range from 573K up to 750K are presented. After these heat treatments the alloys remain in the amorphous state. The accumulative annealing for 15min at 573K and then 600K of the Fe86Zr7Nb1Cu1B5 and Fe81Zr7Nb1Cu1B10 alloys causes the narrowing of the transmission Mössbauer spectra as compared to the as-quenched state and the decrease of the average hyperfine field induction which is connected with the invar effect. For similar behavior in Fe81Pt5Zr7Nb1Cu1B5 alloy the accumulative annealing up to 700K is needed. With further increase of the annealing temperature up to 750K the broadening of the Mössbauer spectra and the increase of the average hyperfine field induction occur. The lowest value of the average hyperfine field induction of amorphous samples is accompanied by the lowest value of the Curie temperature. The investigated amorphous alloys do not reach the magnetic saturation up to the magnetizing field of 2T and the coefficient in Holstein–Primakoff term is about one order in magnitude larger than in other classical FeCo-based amorphous alloys due to the non-collinear magnetic structure. The Mössbauer spectra and hysteresis loops of the amorphous Fe86Zr7Nb1Cu1B5 alloy in the as-quenched state and after the accumulative annealing at 573+620K for 15min are sensitive to the tensile stresses subjected to the sample. Such behavior is ascribed to the invar anomalies. [ABSTRACT FROM AUTHOR]

Abstract: The microstructure and magnetic properties, i.e. the initial magnetic susceptibility, its disaccommodation, core losses and approach to ferromagnetic saturation of the bulk amorphous and partially crystallized Fe61Co10Zr2.5Hf2.5Nb2W2B20 alloy are studied. From X-ray, Mössbauer spectroscopy and electron microscopy studies we have stated that all samples in the as-quenched state are fully amorphous. However, after annealing the samples at 850K for 30min the crystalline α-FeCo grains embedded in the amorphous matrix are found. Moreover, from Mössbauer spectra analysis we have stated that the crystalline phase in those samples exhibits the long-range order. The alloy in the as-quenched state shows good thermal stability of the initial magnetic susceptibility. Furthermore, the intensity of the magnetic susceptibility disaccommodation in the rod is lower than in the ribbon. It is due to low quenching rate during the rod preparation which involves the reduction of free volumes. From the analysis of the isochronal disaccommodation curves, assuming the Gaussian distribution of relaxation times, we have found that activation energies of the elementary processes responsible for this phenomenon range from 1.2 to 1.4eV. After the annealing of the samples the initial susceptibility slightly enhances and disaccommodation drastically decreases. From high-field magnetization studies we have learned that the size of structural defects depends on the quenching rate (the shape of the samples) and changes after annealing. [Copyright &y& Elsevier]

Abstract: Microstructure, revealed by X-ray diffraction, transmission electron microscopy and Mössbauer spectroscopy, and magnetic properties such as magnetic susceptibility, its disaccommodation, core losses and approach to magnetic saturation in bulk amorphous (Fe0.61Co0.10Zr0.025Hf0.025Ti0.02W0.02B0.20)100−x Y x (x=0, 2, 3 or 4) alloys in the as-cast state and after the annealing in vacuum at 720K for 15min. are studied. The investigated alloys are ferromagnetic at room temperature. The average hyperfine field induction decreases with Y concentration. Due to annealing out of free volumes its value increases after the heat treatment of the samples. The magnetic susceptibility and core losses point out that the best thermal stability by the amorphous (Fe0.61Co0.10Zr0.025Hf0.025Ti0.02W0.02B0.20)97Y3 alloy is exhibited. Moreover, from Mössbauer spectroscopy investigations it is shown that the mentioned above alloy is the most homogeneous. The atom packing density increases with Y concentration, which is proved by the magnetic susceptibility disaccommodation and approach to magnetic saturation studies. [Copyright &y& Elsevier]

Abstract: We have found that after the annealing of as-quenched ( or Nb) samples at 573K for 1h the decrease of the average hyperfine field due to the invar effect occurs. It is accompanied by the drop of high-magnetic field magnetization. Moreover, the magnetization of as-quenched and annealed at 573K samples of ( or Nb) alloys does not reach the saturation state in the magnetic field up to 1670kA/m. The crystalline -FeCo phase in the nanocrystalline alloy is atomically ordered. The broad maximum in the isochronal disaccommodation curves was observed for the nanocrystalline alloy, in contrary to ( or Nb) alloys. [Copyright &y& Elsevier]

Abstract: We have found that Co concentration in the crystalline -FeCo phase strongly depends on the chemical composition of the amorphous alloys. From Mössbauer spectroscopy investigations, we have stated that -FeCo phase in the nanocrystalline alloys is atomically ordered. The nanocrystalline alloys exhibit the broad disaccommodation spectrum. This behaviour has not been observed in the nanocrystalline alloy. [Copyright &y& Elsevier]

We stated that crystalline grains in the nanocrystalline alloys obtained by a proper annealing consist of the ordered α-FeCo phase. However, in the partially crystallized alloys during a rapid solidification α-FeCo phase is completely disordered. In both, the amorphous and nanocrystalline samples broad disaccommodation spectra are observed. The activation energies of relaxation processes range from 1.00 to 1.34 eV and from 1.47 to 1.82 eV for the amorphous and nanocrystalline samples, respectively. [Copyright &y& Elsevier]

Abstract: Structure relaxations and low-field magnetic properties of the thick amorphous (, 2 or 5) ribbons subjected to accumulative annealing below the crystallization temperature are investigated. From Mössbauer spectroscopy studies we have found that the average hyperfine field slighty increases after the heat treatment of the samples due to structure relaxations. The intensity of the magnetic susceptibility disaccommodation decreases with the thickness of ribbons. It may be connected with annealing out of some free volumes during the sample preparation. Moreover, we have stated that core losses of the investigated alloys are comparable with those of conventional amorphous materials. [Copyright &y& Elsevier]