The economic feasibility of using aluminum as a conductive material is explained by the favorable ratio of its cost to the cost of copper. In addition, one should take into account the factor that the cost of aluminum remains practically unchanged for many years. When using conductive aluminum alloys for the manufacture of thin wire, winding wire, etc. certain difficulties may arise in connection with their insufficient strength and a small number of kinks before fracture. In recent years, aluminum alloys have been developed with strength characteristics that allow them to be used as a conductive material even in a soft state. One of the promising applications of aluminum is the electrical industry. Hence, the development of new alloy compositions based on this metal is very relevant. The temperature dependence of the heat capacity of A7Е grade aluminum alloys with copper was experimentally determined, and changes in their thermodynamic functions were calculated. The studies were carried out in cooling mode using computer hardware and Sigma Plot software. Polynomials were established for the temperature dependence of the heat capacity and changes in thermodynamic functions (enthalpy, entropy, and Gibbs energy) of these alloys and a reference standard (A5N grade Al) characterized by a correlation coefficient Rcorr = 0.992+0.998. It was shown that the heat capacity of A7E grade aluminum decreases with increasing copper content, and increases with rising temperature. The enthalpy and entropy of A7 grade aluminum alloys with copper decrease with increasing copper content, and increase with rising temperature. The value of Gibbs energy is characterized by an inverse relationship.

This article deals with the hydrometallurgical technology of nickel sulfide (NiS) processing, in particular, the effect of electrolyte composition and depassivating additives on the electrochemical behavior of synthesized nickel sulfide. The kinetics and electrochemical behavior of nickel sulfide in sulfate, sulfite, chloride, bichromate, ammonia and copper-containing electrolytes were studied. Possible directions of the process of nickel sulfide anodic dissolution with the release of elemental sulfur and sulfides that contribute to surface passivation were shown. The depassivating effect of additives, in particular NaCl, KBr and K₂Cr₂O₇ was also studied. The results of studies suggest that: potassium bichromate has a depassivating effect on NiS anodic dissolution in Na₂SO₄ and NH4OH; the optimum concentration of potassium bichromate is around ≈30 g/dm³; sulfide sulfur oxidizes to SO₂ ^4- with NiS dissolution in the presence of K₂Cr₂O₇; NiS intensively dissolves in the pure Na₂SO₃ solution with the formation of insoluble Ni²⁺ hydroxy compounds featuring structure changes with changing pH; the combined action of NH₄OH and Na₂SO₃ causes intensive NiS dissolution with the formation of [Ni(NH₃)n]²⁺ ammonia complexes; the presence of acid anions capable of complexation with both Cu(I) and Cu(II) in copper-containing electrolytes leads to accelerated NiS anode dissolution; the most significant anode dissolution rates are observed in case of a nitrate-bromide system; molten sulfur formed on the NiS surface completely displaces, and copper-bromide complexes dissolve the Cu₂S film formed at low potentials; when 200 g/dm³ of KBr is added to 96.8 g/dm³ of Cu (NO₃)², greater NiS dissolution rates are observed than when 200 g/dm³ of NaCl is added to 67,22 g/dm³ of the CuCl₂ solution.

The stress-strain state of the aluminum-copper bimetal blank flange was studied when extracting boxes rectangular in plan. The studies were carried out using the grid method with assumptions about the material isotropy and incompressibility; uniform deformation within each cell; monotonous deformation, plane stress and three-dimensional strain state, while elastic strains were neglected. A CAD modeling program was used to minimize coordinate grid measurement errors and reduce the time for processing the information obtained. The blanks were rectangles of certain sizes with an explosion-welded AD aluminum and M4 copper layers subjected to preliminary heat treatment before the drawing operation. Rectangular blanks were successively drawn to a height of 10 mm with grid and test sample thickness measurements after drawing. Blank samples were photographed with the same focal length and loaded into the application program. In the program, coordinate points were applied to grid nodes with the distances and coordinates of these points measured before and after strain. According to measurement results, the highest strain was observed in the blank corner areas where compressive stresses increased from the angle bisector to the walls. These stresses led to bimetallic blank stratification and corrugations formed along the copper layer. 20 blanks were drawn, and corrugation was observed on the flange in each case. Varying the hold-down pressure from 0.25 to 0.5 MPa gave no positive results. The highest strain intensity is observed at the end part of the box flange, and this value decreases by 20 % at the approach to the die hole. The effect of angular shear stresses leads to a discontinuity in the transition zone featuring by the presence of an intermetallic layer with reduced plastic properties.

Multicomponent alloys without a base element, also known as high-entropy alloys, are of great interest for research. This paper studies the microstructure of the Fe₂₀Ni₂₀Co₂₀Cu₂₀Al₂₀ alloy in a cast, annealed and deformed state, as well as its mechanical properties and hot deformation ability. This alloy is one of the typical representatives of the high-entropy alloy family. Samples were melted in a vac induction furnace in an argon atmosphere, and then cast into a copper mold. Differential scanning calorimetry results were used to determine the solidus temperature. Homogenization annealing of cast samples was carried out in a high-temperature batch furnace in air. The alloy microstructure was studied by scanning electron microscopy and X-ray diffraction. Electron microprobe analysis using energy dispersive X-ray spectroscopy was used to determine the chemical composition of phases formed. It was shown that crystallization results in the formation of three solid solutions, one with a BCC and two with a FCC crystalline structure. Mechanical properties were studied using uniaxial compressive strength and hardness tests. Deformation tests were carried out on a DIL805A/D quenching and deformation dilatometer and a Gleeble 3800 thermal-mechanical physical simulation system at temperatures of 900 — 1100 °C and strain rates of 0.1—10.0 s^—1 for a true strain degree of up to 1. Optimal homogenization annealing modes for the typical representative of high-entropy alloys, and optimal deformation modes were selected to obtain high mechanical properties.

The paper shows the possibility of obtaining the HfTaTiNbZr high-entropy alloy (HEA) of equimolar concentration from powder components using the method of high-energy ball milling (HEBM) and spark plasma sintering (SPS). Initial powders were processed for 20, 40, 60 and 90 min in a high-energy planetary ball mill. The surface morphology, microstructure, and phase composition studies of HEA samples showed that an HfTaTiNbZr multicomponent powder mixture undergoes significant structural changes during the HEBM process. It was found based on the X-ray phase analysis data that mill processing for 20 min leads to the formation of a solid solution based on Hf (Fm3m) with an FCC structure. Subsequent HEBM for 40 min contributes to the appearance of a solid solution based on Ta (Im3m) with a BCC structure. After 60 min of processing, the peaks of Hf and Ta based solid solutions on the X-ray diffraction pattern completely merge to form one common asymmetric peak within the ~35+51° angle range. It was found that the HfTaTiNbZr HEA with a BCC structure is formed after 90 min of HEBM. According to scanning electron microscopy (SEM), the material has a homogeneous structure, and EDX results showed that the initial elements of Ti, Hf, Ta, Nb, Zr are uniformly distributed in the material volume. Powders obtained after 90 min HEBM were sintered at t = 1150 and 1350 °C for 10 min. The X-ray phase analysis, SEM and EDX results of high-entropy alloys consolidated by the SPS at t = 1350 °С showed that the material mostly consists of one phase with a BCC structure and a small amount of Hf₂Fe and ZrO. The hardness of the sintered HEA (10.7 GPa) exceeded the hardness of the material consolidated from initial element mixture (6.2 GPa) by 1.8 times. Densities of samples sintered at t = 1350 °С from the initial and HEA powders were 9.49 g/cm³ (95.8 %) and 9.87 g/cm³ (99.7 %), respectively.

The study covers the effect of titanium and titanium hydride additives on the structure, mechanical properties, and wear resistance of copper alloys to be used as a binder for diamond cutting tools. Cu-Ti and Cu–TiH₂powder mixtures were obtained by mechanical alloying in a planetary ball mill. This treatment made it possible to obtain single-phase copper-based solid solution powders in the Cu-Ti system and two-phase copper-based powders with uniformly distributed submicron TiH₂ particles in the Cu-TiH₂ system. It was found that Cu-2.5%Ti and Cu-10%TiH₂ compact samples feature by maximum mechanical properties (2.0-3.5 times higher than that of pure copper). Hardening in these alloys is implemented by the solid-solution mechanism and due to the Cu₃Ti₃O phase formation. Grains of this phase have a higher dispersion in alloys with TiH₂ used as a titanium-containing additive. This provides a high value ofbending strength (920 MPa) and hardness (114 HB). According to the results of comparative tribological tests, it was found that Cu—10%TiH₂ samples have the best wear resistance. After pin-on-disk tests, the equivalent wear of these samples was an order of magnitude less than that of pure copper and 5 times lower than that of Cu—2.5%Ti samples.

A relatively new and promising approach to the development of new metal alloys with a view to replacing a number of existing commercially used alloys is the use of a new alloying concept based on the development of metal materials comprising several basic elements taken in approximately equal atomic concentrations. Such materials are called high-entropy alloys (HEA). Modern research has shown that the HEA microstructure can be formed by solid solutions with both BCC and FCC lattices, and also have ordered phases (intermetallics) in its composition. This approach to forming metal materials provides a wide range of opportunities for the development of new alloys with improved performance. Most of the current HEA research is focused on identifying a relationship between the microstructure and measured properties. Much less attention is paid to the study and development of new effective methods for HEA production. This paper investigates the possibility of obtaining HEA based on the CoCrFeNiMn-(X) system in the combustion mode using centrifugal SHS metallurgy methods. For the first time, the study made it possible to practice chemical technology methods of cast CoCrFeNiMn alloy modification directly (in situ) during synthesis by introducing alloying components into the original exothermic compounds. The microstructure and phase composition ofNiCrCoFeMn alloys obtained with the introduction ofthe Ti—Si—B(C) complex modifying additive and NiCrCoFeMn—Al_x excess aluminum were analyzed. The obtained data indicated that as the Ti—Si—B(C) additive content increases, the microstructure of synthesis products is formed based on a matrix of HEA with evolving new structural elements based on carbides and Ti borides. It was found that synthesis in the combustion of alloys with a high Al concentration (x > 0.6) leads to the formation of a composite structure consisting of the NiAl-based matrix with numerous nanoscale (~100 nm) dispersive precipitates formed from the Cr and Fe based solid solution. The obtained experimental data allows us to conclude that the HEA-based materials under study and the proposed method for obtaining them to form bulk nanostructural HEA-based materials have promising prospects.