Vol 2017, No 8 (2017)

The volumetric thermal expansion coefficients of the equiatomic Na–K and K–Rb melts at 373 K are calculated using variational method with an additive hard-sphere reference system. It is found that the Krasko–Gurskii model pseudopotential with the exchange-correlation Geldart–Vosko function yields better agreement with the experimental data as compared to the local Animalu–Heine pseudopotential with the exchange-correlation Toigo–Woodruff function.

The mechanism of formation of ceramic microparticles (alumina) and graphene in a molten aluminum matrix is studied as a function of the morphology and type of precursor particles, the temperature, and the gas atmosphere. The influence of the composition of an aluminum composite material (as a function of the concentration and size of reinforcing particles) on its mechanical and corrosion properties, melting temperature, and thermal conductivity is investigated. Hybrid metallic Al–Al₂O₃–graphene composite materials with up to 10 wt % alumina microparticles and 0.2 wt % graphene films, which are uniformly distributed over the metal volume and are fully wetted with aluminum, are synthesized during the chemical interaction of a salt solution containing yttria and boron carbide with molten aluminum in air. Simultaneous introduction of alumina and graphene into an aluminum matrix makes it possible to produce hybrid metallic composite materials having a unique combination of the following properties: their thermal conductivity is higher than that of aluminum, their hardness and strength are increased by two times, their relative elongation during tension is increased threefold, and their corrosion resistance is higher than that of initial aluminum by a factor of 2.5–4. We are the first to synthesize an in situ hybrid Al–Al₂O₃–graphene composite material having a unique combination of some characteristics. This material can be recommended as a promising material for a wide circle of electrical applications, including ultrathin wires, and as a structural material for the aerospace industry, the car industry, and the shipbuilding industry.

The kinetics of thermal diffusion boriding in a melt based on calcium chloride with a boron oxide additive is studied using reversed current. The main temperature, concentration, and current parameters of the process are determined. The phase composition of the coating is determined by a metallographic method.

The modeling of zirconium reduction from oxide by thermal analysis shows that the congruently stable intermetallic compound Al₃Zr is formed as a result of the process. The formation of Al₃Zr proceeds via the stage of formation of intermediate zirconium monoxide.

The interaction in the Hf–C system during mechanical activation performed in a high-energy planetary ball mill and the irradiation-assisted fabrication of hafnium carbide from an Hf/C mechanocomposite are studied by synchrotron X-ray diffraction (at a quantum energy of 33.7 keV) and high-resolution scanning electron microscopy. The mechanochemical interaction results in the formation of an Hf/C mechanocomposite at the first stage and mechanical activation for ≥8 min forms hafnium carbide. The irradiation of the Hf/C mechanocomposite with a high-energy electron beam (~150 W/mm²) causes melting and spreading of hafnium over the carbon particle surface and the crystallization of hafnium carbide.

The dependences estance vs. potential in molten LiCl are obtained. They have three zeros of estance near the melting temperature of the salt. When the temperature increases by 400 K, only one cathode zero is retained for equilibrium estance. A comparison of the potentials of this zero of estance in a row of alkali metal chlorides at the same temperature indicates their nonmonotonic dependence on the cation radius, in contrast to the potentials of the ECC maxima of liquid Pb, Bi, and In and the PZC of gold in this row.