Vol 117, No 5 (2016)

The size dependences of the Fermi energy of metallic films of Al and Pb bordering with the dielectrics SiO₂, Al₂O₃, HfO₂, ZrO₂, and TiO₂ have been calculated. The model of free electrons and an asymmetric potential well has been modified by the introduction of the effective masses of electrons in the metal and in the insulator. The evolution of the size oscillations of the Fermi energy of metallic films in different dielectric surroundings upon the variation of the effective masses of electrons both in the metal and in the insulator has been analyzed. It has been shown that the allowance for the effective mass of electrons in the metal leads to a more substantial change in the position of the Fermi level in comparison with the allowance for the effective mass of the dielectric.

Magnetocaloric effects (MCEs) in two-sublattice anisotropic antiferromagnets with single-ion anisotropy of easy-axis type have been investigated upon orientation of a magnetic field both along and transversely to the easy axis of magnetization. It has been shown that MCEs that arise in a longitudinal magnetic field in the paramagnetic range above the Néel temperature T_N are of a normal character, whereas in low fields in the magnetically ordered range below T_N, they are anomalous: isothermal magnetization increases magnetic anisotropy and adiabatic magnetization reduces the temperature of the antiferromagnet. Upon the magnetization of anisotropic antiferromagnets perpendicular to the easy axis of magnetization above the Néel point T_N, we observe normal (direct) MCEs that are weaker than in longitudinal fields and decrease with the relative growth of the single-ion anisotropy parameter D > 0. In low fields, upon magnetization by transverse fields below T_N, as in the case of longitudinal magnetization, anomalous (inverse) MCEs arise, but they are several orders of magnitude weaker than analogous effects in longitudinal fields and disappear completely upon passage to the limiting case of isothermal antiferromagnet.

The magnetic dynamic response of a PrB₆ single crystal has been studied using inelastic neutron scattering in a temperature range of 10–120 K, which is above the temperatures of the phase transitions to the magnetic-ordered state. The study is aimed at revealing peculiarities of the state with a low magnetic moment in a temperature range of 7 K < T ≤ 20 K, which was identified in a number of magnetometric experiments. In addition to a quasielastic signal, a weak-dispersion excitation with an energy of ~1 meV has been detected, which exists at temperatures below 24 K. The results have been analyzed from the viewpoint of the formation of a spatially nonuniform state based on domains with short-range magnetic correlations at temperatures of 10–20 K. Judging by the dispersion of excitations, the character of the correlation is similar to that observed in a state with long-range magnetic order which arises at lower temperatures.

In the present study, Chou’s General Solution Model (GSM) has been used to predict the enthalpy and partial enthalpies of mixing of the liquid Ag–In–Sn ternary, Ag–In–Sn–Zn quaternary, and Ag–Au–In–Sn–Zn quinary systems. These are of technical importance to optimize lead-free solder alloys, in selected cross-sections: x_In/x_Sn = 0.5/0.5 (ternary), Au–In_0.1–Sn_0.8–Zn_0.1, Ag–In_0.1–Sn_0.8–Zn_0.1 (quaternary), and t = x_Au/x_In = 1, x_In = x_Sn = x_Zn (quinary) at 1173, 773, and 773 K, respectively. Moreover, the activity of In content in the ternary alloy system Ag–In–Sn has been calculated and its result is compared with that determined from the experiment, while the activities of Ag contents associated with the alloys mentioned above have been calculated. The other traditional models such as of Colinet, Kohler, Muggianu, Toop, and Hillert are also included in calculations. Comparing those calculated from the proposed GSM with those determined from experimental measurements, it is seen that this model becomes considerably realistic in computerization for estimating thermodynamic properties in multicomponent systems.

The structure and texture in the Ni–30% Co alloy subjected to cold rolling and annealings in strong dc magnetic field at the temperatures of above and below the Curie point are studied. It has been shown that, at all annealing temperatures, the average grain size after magnetic annealing is smaller than after annealing without filed. After the magnetic annealing of the alloy in the ferromagnetic state, the volume fraction of grains with cube orientation decreases and the volume fraction of the components of deformationinduced texture increases.

Cu + Cr₃C₂ composites have been produced using the mechanical alloying of the elemental components, followed by severe plastic deformation by torsion, magnetic-pulse pressing, and electric-pulse plasma sintering. The composites are studied using X-ray diffraction and light and electron microscopy, as well as measurements of the hardness, density, and electric conductivity. Magnetic-pulse pressing at a temperature of 500°C makes it possible to produce volume nanocomposites with a homogeneous distribution of dispersed carbides over the copper matrix, which has a density of 96%, a Vickers microhardness of 4.6 GPa, a Rockwell hardness of 69 HRA, and an electric conductivity of 19% IACS units. Using electric-pulse plasma sintering at a temperature of 700°C, composites with the nanostructured copper matrix, which contains carbide inclusions and consists of domains surrounded by a layer of nearly pure copper, have been produced. These composites have a density of 88%, a Vickers microhardness of 4.0 GPa, a Rockwell hardness of 58 HRA, and electric conductivity of 26% IACS units.