Viscosity of liquid alumentric composite Al–7% Si + 5% Al2O3

A. B. Finkelstein, O. A. Chikova, M. Makhmudzoda, V. V. Viukhin

ABSTRACT

The kinematic viscosity of a liquid aluminum matrix composite (Al–7% Si + Al2O3) obtained by the method of purging a pre-hydrogenated melt with oxygen was studied using the method of torsional vibrations in comparison with the initial alloy. The photometric method revealed the proportion of oxide particles in the aluminum matrix. The absence of branching of polytherm melt composite material, which is associated with its inherent microheterogeneity. The possibility of predicting the viscosity of a composite material from known dependencies is shown, taking into account the fragmentation shape of the particles of the dispersed phase. The obtained data can be used to calculate the gating systems.

KEYWORDS

composite material, particles, dispersion medium, kinematic viscosity, Einstein equation, microheterogeneity

DOI: 10.1134/S0235010619040042

Features of the aluminothermal restoration of titanium in the presence of tantal and vanadium oxides

L. B. Vedmid’, E. M. Zhilina, T. V. Osinkina, S. A. Krasikov, S. V. Zhidovinova, E. V. Nikitina

ABSTRACT

Theoretical and experimental modeling of the joint aluminothermic reduction of titanium and tantalum, titanium and vanadium from their pentooxides has been performed. The sequence and features of the formation of compounds in the systems Al–TiO2–Ta2O5 and Al–TiO2–V2O5 are established.

KEYWORDS

alloy, aluminothermic reduction, intermetallic compounds, phase formation

DOI: 10.1134/S0235010619040133

Microstructure of high-strength aluminum alloy after combined surface strength

S. G. Kuptsov, A. V. Elantsev, E. A. Nikonenko, E. V. Nikitina, A. V. Shak, N. A. Kazakovtseva

ABSTRACT

Metallographic studies of carbidoboride coatings on samples of aluminum alloy V96Ts, applied from both sides by the method of electric spark alloying (ESA), were performed. On one side, the coating was further processed with a laser. It is established that the surface with ESA has significant irregularities, pores, cracks, and laser treatment leads to a decrease in roughness. Laboratory tests allowed recommending a combined (electric-spark-laser) method of hardening the surface of specimens of aluminum alloy V96Ts to increase the service life of tools and machine parts.

KEYWORDS

coatings, doping, laser processing, carbidoborides, aluminum

DOI: 10.1134/S0235010619040108

Influence of accounting of non-diagonal d–d-electron couplings on the effective pair interaction in the equatomonic Cu–Ag alloy

N. E. Dubinin

ABSTRACT

Within the framework of the Wills–Harrison model, the effect of taking into account d-electron overlaps between two neighboring atoms off-diagonal in terms of the magnetic quantum number on the effective pair interaction in an equiatomic Cu–Ag melt near the melting point has been studied. It was found that an increase in the share of off-diagonal overlaps leads to an increase in the depth of the first minimum and to a shift of its coordinate towards smaller values of the interatomic distance for all three partial pair potentials.

KEYWORDS

transition-metal melts, Wills–Harrison model, model Bretonnet–Silbert pseudopotential, d–d electron overlap, effective pair interaction

DOI: 10.1134/S0235010619040030

The Wills–Harrison effective pair interaction in liquid Au

N. E. Dubinin, G. M. Bhuiyan, F. I. Abbas

ABSTRACT

The Wills–Harrison effective pair interaction in liquid Au near the melting temperature is studied. It is found that its dependency on the portion of the non-diagonal, with respect to the magnet quantum number, d-electron couplings between two neighboring atoms has another behavior than in melts of 3dCtransition metals.

KEYWORDS

gold, liquid noble metal, Wills–Harrison effective pair interaction, Bretonnet–Silbert model pseudopotential, d–d-electron couplings

DOI: 10.1134/S0235010619040029

Changes in structural and dynamic characteristics of metal melts, glasses and nanocrystals depending on temperature and hydrogenation

N. A. Vatolin, V. A. Polukhin, N. I. Sidorov

ABSTRACT

Researchers conducted a comprehensive analysis of both the original material and the available information on phase-structural transformations during cooling, glass transition and crystallization of melts, with detailed tracking of their ordering methods using synchrotron X-ray diffraction, scanning electron microscopy, DSC calorimetric measurements, and interpretation of data by modeling and thermodynamic by calculations.

KEYWORDS

melts, amorphous alloys, vitrification, X-ray diffraction, DSC calorimetry, medium order, structural factor, heat capacity, hidden liquid transitions, viscosity, diffusion, crossover

DOI: 10.1134/S0235010619040121

Kinetic of zirconium and aluminium electrowinning from the KF–AlF3–ZrO2 melts

A. A. Filatov, A. V. Suzdaltsev, A. Yu. Nikolaev, Yu. P. Zaikov

ABSTRACT

Kinetics of zirconium and aluminum electroreduction from the KF–AlF3–Al2O3–ZrO2 melts at a temperature of 750°C have been studied by means of voltammetry methods and stationary polarization. The effects of the ZrO2 additions, substrate material and polarization rate on the kinetics and the main features of the zirconium and aluminum electroreduction under stationary and nonstationary conditions were studied. It was shown that the zirconium electroreduction is primary accompanied by diffusion difficulties and it is not reversible. The limiting currents of the cathode process in the KF–AlF3–Al2O3–ZrO2 melts as well as diffusion coefficients of zirconiumEcontaining electroactive ions were estimated, depending on the ZrO2 content in the melts under study. The results obtained were used for electrolysis tests. A new method for Al–Zr master alloys production from oxides during electrolysis of the KF–AlF3Ebased melts was proposed.

KEYWORDS

aluminium, zirconium, master alloy, melt, KF–AlF₃–Al₂O₃, cathode process, electroreduction, voltammetry

DOI: 10.1134/S0235010619030046

Features of technical silicon cleaning in melting in helium with impact on electric field melt on molybdenum and graphite electrode

A. V. Kaibichev, I. A. Kaibichev

ABSTRACT

The features of the purification of technical silicon in helium with molybdenum and graphite cathodes are considered. The formation of silicides and carbides in the melt is substantiated. The effect of melt polarity on the removal of impurities and gases is shown. The evaporation of technical silicon and the interelectrode transfer of elements are quantitatively determined. The efficiency of evaporation and removal of impurities in an electric field is estimated.

KEYWORDS

iron, titanium, silicon, silicides, carbides, melt, electricity

DOI: 10.1134/S023501061903006X

Dynamics of cluster structure change in melts that forms a continuous series of solid solutions during equilibrium and nonequilibrium crystallization

V. D. Aleksandrov, S. A. Frolova, A. P. Zozulya

ABSTRACT

The scheme of a cluster structure of melts that forms a continuous series of solid solutions in the overheated and overcooled states concerning liquidus temperatures is developed. Structure change dynamics of clusterized liquid during cooling and further equilibrium and nonequilibrium crystallization is analyzed. Coexistence areas of liquid solution with clusters, nucleus and a solid phase are designated. Borders of a clustering and a way of their transformation to nucleus and crystals of solid solutions are defined. The thermograms of cooling characterizing different types of crystallization of alloys are considered. On their basis the analysis of ways of crystallization according to state diagram is given.

KEYWORDS

melts, binary system, alloys, solid solutions, state diagram, solubility, entropy, clusters, clustering, nucleus, equilibrium and nonequilibrium crystallization, thermograms

DOI: 10.1134/S0235010619030034

Thermal researches of the process of obtaining magnesium master alloy with ittrium and zinc

S. А. Savchenkov, V. Yu. Bazhin, V. N. Brichkin, V. L. Ugolkov

ABSTRACT

Using thermal analysis (DTA), processes occurring during the interaction of yttrium fluoride melts with sodium fluoride and potassium chloride, used as a flux in the metallothermic synthesis of the Mg–Y master alloy, were investigated. In addition, to identify patterns of magnesium thermal reduction of yttrium from the salt mixture, thermal studies of the interaction of yttrium and sodium fluoride salt systems and potassium and sodium chlorides with magnesium and zinc were carried out.

KEYWORDS

magnesium master alloy, master alloy magnesium–zinc–yttrium, thermal analysis, magnesium thermal reduction, synthesis

DOI: 10.1134/S0235010619030095