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The influence of the elemental composition of strip amorphous alloys Fe80.0Si6.0B14.0, Fe78.5Ni1.0Mo0.5Si6.0B14.0; Fe73.1Cu1.0Nb3.0Si15.5B7.4; Fe51.7Ni21.7Cr6.2Mo0.6V1.5Si5.2B13.1 on corrosion resistance in 0.5 M aqueous solutions of NaCl, HCl, and KOH at T = (293 ± 1) K was investigated. The high corrosion resistance of Fe51.7Ni21.7Cr6.2Mo0.6V1.5Si5.2B13.1 and Fe73.1Cu1.0Nb3.0Si15.5B7.4 alloys in aggressive environments was established. Electrochemical parameters obtained both by the method of cyclic voltammetry and electrochemical impedance spectroscopy (EIS) indicate the formation of more durable surface layers in a 0.5 M potassium hydroxide aqueous solution on these alloys. The Cl– ions (especially at low pH) under their long-term action are the more aggressive oxidizers of amorphous alloys compared to OH– ions. During the passivation film formation in highly aggressive environments such alloy elements, which do not participate in this process, actively dissolve, and the main film-forming elements accumulate under the film, thus improving its protective properties. [ABSTRACT FROM AUTHOR]

By the method of cyclic voltammetry, we study the corrosion resistance of amorphous and crystalline Al87Ni8Y5 alloys in a 0.5 M aqueous NaCl solution for different sweep rates of potential of the electrode surface (10, 20, 50, and 100 mV/sec). We find the electrochemical characteristics of crystalline Al, Ni, and Y in solutions of sodium chloride. The diffusion coefficients of Al3+ and Ni2+ ions are determined. It is shown that the alloys are ionized in this solution in three stages and the diffusion rate of Al3+ from the near-electrode layer is lower than for Ni2+ ions. [ABSTRACT FROM AUTHOR]

The literature data on the problem of modification of the structure and properties of the Fe-based rapid-quenched alloys by various methods of severe plastic deformation (SPD) are reviewed. The SPD methods such as Bridgman cell torsion, ball-mill processing and high-frequency shock treatment as well as their advantages and disadvantages are considered. By examples of a large number of amorphous Fe-based alloys, the influence on their structure and properties of each of the considered SPD methods is analysed. Based on the obtained data, the mechanism of deformation nanocrystallization of amorphous alloys is proposed. [ABSTRACT FROM AUTHOR]

The methods of chronopotentiometry and cyclic voltammetry are used to study the electrochemical characteristics of bulk and strip specimens of FeMnMoCrCPBSi(Cu,W, Al) amorphous metallic alloy in a 0.5 M aqueous solutions of sodium chloride, potassium hydroxide, and hydrochloric acid. It is shown that, in corrosive aqueous solutions, the surface of the strip specimen is more stable than the surface of the bulk specimen with the same composition. The computed values of the activation energy of the processes of dissolution of the bulk specimen in corrosive media with different compositions reveal the elevated corrosion resistance of the investigated material. [ABSTRACT FROM AUTHOR]

According to the data of chronopotentiometric measurements of the behavior of free potential and the results of cyclic voltammetry of FeNbB (Dy, Tb) electrodes (made of amorphous metallic alloys) in aqueous solutions of NaCl, NaOH, and KOH, we determine the principal electrochemical characteristics of their corrosion resistance. The procedure of doping of the amorphous metallic alloys with terbium guarantees the highest protective properties, which is explained by its insolubility and high adhesion of its oxidation products to the surface. [ABSTRACT FROM AUTHOR]

Powder metallurgy methods are used to produce soft magnetic compact materials from amorphous and nanocrystalline alloys. Toroid-shaped samples are warm-pressed from nanocrystalline FeSiBCuNb alloy powders and SFP-012A resin binder. The method does not require additional thermal treatment and the samples are ready to use. The key influence on the properties of soft magnetic powder materials is produced by ferromagnetic filling factor (FFF). The optimal experimental conditions to make samples with the minimum porosity and maximum FFF are determined. The density of the samples depending on compaction parameters and resin content is established. [ABSTRACT FROM AUTHOR]

The oxidation of aniline is studied by the potentiodynamic method on an electrode of an amorphous metallic alloy AlNiY and the results are compared with the analogous data on a polycrystalline aluminum electrode. The aniline oxidation and, correspondingly, the polyaniline deposition are shown to proceed more actively on the contact side of the amorphous metal alloy AlNiY electrode. The morphology of synthesized polyaniline films is studied on both sides of the working electrode. It is found that the polyaniline layer structure is to the large extent granulated on the contact side and smooth on the external side. [ABSTRACT FROM AUTHOR]

Abstract: In the present paper the influence of RE alloying additions (Y, Gd, Tb and Dy) on magnetic properties (Curie temperatures, low temperature magnetization, zero field cooling–field cooling curves, domain structure, room temperature magnetostriction and magnetic permeability) of amorphous alloys of type Fe82Nb2B14RE2 are carefully examined. It was shown that substituting of yttrium atoms by magnetic elements, i.e. Gd, Tb and Dy leads to (i) an increase of the Curie temperature of amorphous phase from 416K (for Fe82Nb2B14Y2) to 450K (for Fe82Nb2B14Gd2) and (ii) a decrease of magnetization in saturation (magnetic field 7T) which can be explained by antiferromagnetic Fe–RE coupling resulting in a decrease of magnetic moment calculated per magnetic atom from 2.00μB for the Fe82Nb2B14Y2 alloy (Fe in amorphous phase) to 1.51μB for the Fe82Nb2B14Tb2 alloy. It was concluded that Tb and Dy alloying additions introduce a local magnetic anisotropy responsible for significant decrease of initial magnetic permeability (about 5 times in relation to Fe82Nb2B14Y2 or Fe82Nb2B14Gd2 alloy), increase of magnetic irreversibility effect measured at 2K (about 10 times in relation to the same alloys) and appearing of the finger-print magnetic domain regions (not observed for the Fe82Nb2B14Y2 and Fe82Nb2B14Gd2 alloys). [Copyright &y& Elsevier]

Structural changes of rapidly cooled ribbons of the amorphous alloys Al(Ni,Co,Fe)(Y,Gd,Nd,La), which occur during heating at a rate of 10 K/min and lead to a loss of ductility, have been investigated experimentally. It has been shown that samples of the studied alloys are divided into two groups, in the first of which the loss of ductility is due to the formation of a nanocomposite structure, whereas the embrittlement of samples in the second group is caused by processes of structural relaxation in the amorphous phase (decrease in the concentration of a free volume). It has been established for the first time that there is an empirical correlation between the dynamic temperature, after heating to which the alloys lose their ductility at room temperature, and the ratio of the shear modulus to the elastic modulus of the alloys, which is calculated from the nominal chemical composition. [ABSTRACT FROM AUTHOR]

Amorphous metallic alloys (AMAs) AlYNi, AlGdNi, AlYGdNi, AlYGd1NiFe, and AlGdNiFe produced by melt spinning on a cooled substrate have been studied. Based on the data of differential scanning calorimetry and X-ray diffraction, the activation energies of individual stages of crystal-lization, the sizes and volume fractions of nanocrystals in an amorphous matrix have been calculated. The alloying of AMAs with Y or Gd is shown to lead to the formation of particles with sizes of 9-15 nm at the first stage of nanocrystallization, which provides their high microhardness. [ABSTRACT FROM AUTHOR]