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Formation of the structure and properties of multi-component iron based alloys in dependence on the conditions of the solidification of hydrogenated melts

R. M. Belyakova, V. A. Polukhin, N. I. Sidorov.

ABSTRACT:

The regularities of the behavior of the absorbed surfactant element (p.a.e.) of hydrogen on the peculiarities of the formation and phase structure in the multicomponent systems based on iron: steel, cast iron and alloys of the FINEMET group were studied. An analysis of the diffusion activity of elements with hydrogen adsorbed on them, hydrogen permeability, types of interatomic bonds as a result of interaction of elements and their influence on the functional properties of the products of structural design are carried out. The purpose of the work is to establish the nature of the interatomic bonds of adsorbed on the elements of the multi-component iron alloys of surface-active hydrogen and its influence on the functional and operational properties of the metal products under the changing conditions of their

structuring.

KEYWORDS:

interatomic interactions, types of bonds, polymorphic phase transitions, hydrogen, nanostructured phases, ferrite, graphite, carbides, structure and properties of matrices in products

DOI: 10.1134/S023501061805002X

The effect of calcium-containing additives on the extraction of alumina from red muds of alumina production

S. A. Bibanayeva, V. N. Koryukov, V. M. Skachkov, N. A. Sabirzyanov, V. M. Ufimtsev, E.M. Lebedeva

ABSTRACT

The results of an experimental study of the effect of calcium-containing reagents on the process of high-temperature autoclave extraction of alumina from red muds obtained from Timan deposit bauxites by the parallel Bayer-sintering method are presented. The phase composition of products is determined by XRD and EDXR methods. Increased extraction of alumina from red mud when used the surface-carbonized lime in the process is shown.

KEYWORDS

red mud, processing, leaching, calcium oxide

Peculiarities of self-diffusion and shear viscosity in transition and transition metals

N. P. Malomuzh, V. N. Makhlaychuk

ABSTRACT

The paper discusses the behavior of the coefficients of shear viscosity and self-diffusion in liquid transition and post-transition metals, as well as their melts. It is shown that the application of activation concepts to the description of temperature dependences of the coefficients of shear viscosity and self-diffusion is incorrect. It is established that the shear viscosity of transition and post-transition metals is described with high accuracy by the same formulas as for alkali metals. This means that the key role in the formation of viscosity is played by the effects of the “roughness” of molecular layers shifting relative to each other. It is shown that self-diffusion coefficients should be considered as a superposition of two independent contributions – chaotic local mixing and collective drift, which is a characteristic feature of only the liquid state of matter. The values of the ion radii of the metals under consideration are discussed.

KEYWORDS

self-diffusion coefficient, shear viscosity, liquid transition and post-transition metals

 

Modifiing effect of zarconium oxide nanoparticles in electric arc welding

A. B. Finkelstein, V. V. Kartashev, M. V. Fominykh, E. I. Denisova, A. V. Berezovsky

ABSTRACT

The structure of weld metal, made by flux-cored wire with the addition of 0.3% of zirconium oxide at the beginning of scaly morphology, was investigated. The structure of the seam represents needle ferrite. This can be said that the dissociation of zirconium oxide in an electric arc is not an obstacle to the modifying effect that manifests itself both in the course of the interaction of zirconium with oxygen and in the surface activity of zirconium in a crystallizing melt based on iron. Zirconium oxide, thus, is a modifier of both the first and second kind for the crystallizing weld metal. Excess oxygen, presumably, forms seam pores with a diameter of less than 1 m, which, however, does not significantly affect the mechanical properties of the welded seam. The bottom line: the obtained data will be used in the development of electrode materials for the welding of tubular steels.

KEYWORDS:

electric arc welding, nanoparticles, zirconium oxide, modification, needle ferrite

Production of alloy-coating of nickel-golmium in equimolar melt NaCl–KCl with addition of HoCl3

A. N. Bushuev, O. V. El’kin, I. V. Tolstobrov, A. V. Sazanov, D. A. Kondrat’ev

ABSTRACT

In the present work, the reduction of holmium ions at a nickel electrode in a molten equimolar mixture of sodium and potassium chlorides with the addition of holmium chloride in the temperature range 1073–1173 K was studied by the cyclic voltammetry method. The potentials for the formation of nickel–holmium intermetallic compounds were found. A nickel-holmium alloy was synthesized by potentiostatic electrolysis. It is shown that under the selected conditions of electrolysis the resulting coating is single-phase and corresponds to the composition of HoNi2. The diffusion coefficients of holmium in nickel are calculated and the activation energy of the alloy formation process is determined.

KEYWORDS:

ionic melts, holmium, nickel, cyclic voltammetry, diffusion coefficient, activation energy

Formation of electrode deposit under galvanostatic conditions

V. A. Isaev, O. V. Grishenkova, M. V. Laptev, A. V. Isakov, Yu. P. Zaykov

ABSTRACT

The regularities of the formation of a continuous deposit layer under constant current are considered. The equations for calculation of time dependences of overpotential for instantaneous nucleation with kinetic- or diffusion-controlled growth of a new phase are analyzed. The theoretical dependences are compared with the experimental ones for the electrodeposition of silicon from a fluorideFchloride melt.

KEYWORDS:  electrocrystallization, galvanostatic method, nucleation, growth, continuous layer, melt

Two approaches to the construction of fractals of five-pointed stars

A. A. Polyakov

ABSTRACT

As it have been shown earlier, fractals of five-pointed stars allow to repeat the structure of the Penrose tiling, which is the initial model for the crystal lattice of decagonal quasicrystals. Deflationary and inflationary approaches to the construction the fractals of five-pointed stars are offered. In the deflationary approach, at each stage, the regular five-pointed stars of the same orientation and size are placed so, that their centers coincide with the vertices of the polygons of the previous step. The previous prefractal is deleted. In the inflationary approach, the prefractal of the previous step is replicated and placed so, that its centers are coincided with the vertices of increasing regular five-pointed star. The deflationary approach leads to the fragmentation of the structure, the inflationary approach allows joining the stars into increasing clusters. It is shown, how deflationary and inflationary approaches are related. The absolute and relative descriptions of the fractals of five-pointed stars are also considered. In the absolute description, the absolute size and orientation of the building elements are recorded. In the relative description, there are used the changes of these characteristics at each stage of the fractal construction.

KEYWORDS:

fractals, Penrose tiling, quasiperiodic lattice, quasicrystals.

Influence of the correction to the Wills–Harrison approach on the thermodynamics of liquid Co–Ni alloy

N. E. Dubinin

ABSTRACT

The Helmholtz free energy of mixing for the liquid equiatomic Co–Ni alloy is calculated near its melting temperature in the framework of the modified Wills–Harrison model (Dubinin N.E, J. Phys.: Conf. Series, 2012, 338, 012004) at different values of the probability that not only diagonal couplings between d states of neighboring atoms are possible in transition metal. It is found that an account of non-diagonal d–d couplings leads to an improvement of theoretical results for thermodynamic properties of liquid transition-metal binary alloys.

KEYWORDS: Wills–Harrison approach, d–d coupling, variational method, liquid transition-metal alloy, Helmholtz free energy of mixing.

The first-principle pseudopotential calculations of alkali-alkali liquid alloys thermodynamics

V. A. Krashaninin, N. E. Dubinin

ABSTRACT

Concentration dependencies of the Helmholtz free energy of mixing are calculated for liquid Li–Rb, K–Rb and Li–Na alloys at different temperatures by using the variational method of the thermodynamic perturbation theory and the first-principle pseudopotential with the true wave functions instead of the pseudo-wave ones employed for calculation the screening potential. An excellent agreement with the experimental phase diagram is achieved in description of the phase separation in Li–Rb alloy. The ideal mixing in K–Rb alloy and the phase-separation tendency in Li–Na alloy are obtained only at temperatures that are higher than ones observed experimentally.

KEYWORDS: variational method, first-principle pseudopotential, liquid binary metal alloy, Helmholtz free energy of mixing.