The study described in this paper pertains to production of consolidated materials using the method of self-propagating high-temperature synthesis with subsequent compaction of hot products (SHS compaction). This method applied to mechanically activated Ni + Ti mixtures helps one obtain pore-free titanium nickelide samples with a diameter of 70 mm and a thickness of 8 mm. Ni + Ti combustion occurs in a reaction mold with neither preliminary heating nor a protective medium. The effect of mechanical activation in a ball mill on the mixture characteristics and combustion parameters is studied. As shown by the analysis of the microstructural characteristics, an increase in the reactivity of mechanically activated Ni + Ti mixtures and the implementation of exothermic interaction during self-propagating high-temperature synthesis are due to a decrease in the crystallite size of Ni particles, an increase in their dislocation density, and the formation of composite Ti–Ni particles. The maximum combustion temperature of the reaction mixture is 1150°C, and the average burning rate is 3.5 cm/s. The main phases of the synthesized alloy are Ti2Ni, NiTi, and Ni3Ti. The compressive strength of the samples is 1350 MPa, and the Vickers microhardness is 11.1 ± 1.2 GPa.

A comprehensive methodology for designing a magnetic deflection system for a technological electron gun is proposed. The feasibility of using deflection systems with an internal magnetic circuit and toroidal coil sections to form deflection fields that ensure azimuth beam rotation with a constant angle of deviation from the vertical axis is substantiated. The potential of computer modeling is shown both at the stage of calculating the deflection field and beam displacement and at the stage of creating the design of the system frame for its subsequent manufacture based on 3D printing. The main coil parameters are determined, and the circuit diagram of a current stabilizer with external control from a digital-to-analog converter is developed. Dependences are presented showing the relationship between control signals and deflection angles in the developed unit prototype. It is shown that the proposed technique is universal and can be used to create electron-optical gun elements providing deflection, scanning, parallel transfer or adjustment of technological electron beams.

This paper is concerned with obtaining metal-ceramic composite materials through the method of SHS compaction. The study investigates the influence of mechanical activation of metallic components in reactive mixtures based on the Ti + C + Cr + Ni system on the structure and properties of the resulting composites. Mechanical activation of the Ti, Cr, and Ni metallic powders was performed using two methods. In the first method, Cr and Ni powders were activated separately from the other components of the reactive mixtures using grinding media in a ball mill, after which they were mixed with Ti and carbon black powders. It was shown that the preliminary mechanical activation of the inert components reduces the combustion temperature and rate, which increases the average size of carbide grains. The second method involved a joint processing of Ti + Cr, Ti + Ni, and Ti + Cr + Ni powder mixtures in a ball mill, which were then mixed with carbon black. This method provided mechanical activation of titanium particles while minimizing the impact of grinding media on Cr and Ni powders. This led to an increase in the combustion rate and temperature, a decrease in the average size of carbide grains, and an improvement in the uniformity of the composite structure. A mechanism of interaction between the reagents (Ti + C) involving activated Cr and Ni particles in the combustion and structure formation zones is proposed. According to this mechanism, the mechanical activation of inert components leads to their direct participation in the reaction between titanium and carbon, which determines the reduction in combustion rate and temperature and affects the dispersion and uniformity of the structure of compact composites. The results were used to enhance the uniformity and refine the structure of the STIM-3B composite (synthetic hard tool material grade 3B).

The structure is considered for a typical system to control electron beam welding deposition with supplying feed (wire). This approach is used today to implement additive technologies. The main features of the process are described. It is shown that the temperature of the underlying layer changes during surface deposition; therefore, it destabilizes the process through changing the temperature of the melt bath as well as the transverse dimensions of the formed layer. The need to use a feedback control system to stabilize the temperature of the welded layer is substantiated and an approach to its technical implementation is described. The results obtained for a prototype of a temperature stabilizer based on a microcontroller are presented. The fundamental potential is demonstrated to ensure the repeatability of the height of the welded layer and to prevent the wire from detaching the liquid melt bath during welding deposition of a multilayer cylindrical contour made of 316L steel.

The paper presents the results of an experimental study into the possibility of producing ultra-high temperature ceramics constituting solid solutions of HfC and ZrC carbides by the single-stage electro-thermal explosion (ETE) method under pressure. Adiabatic flame temperature and phase composition of the equilibrium final product were calculated based on thermodynamic data. It was shown that when the ZrC content in the final product is less than 20 wt.%, adiabatic flame temperature reaches 3800– 3900 K, and the combustion product contains hafnium and zirconium carbides. The effect of mechanical activation modes in an AGO-2 planetary centrifugal mill used for a reaction mixture containing Hf, Zr and C powders on its properties, phase composition formation and the microstructure of carbide solid solutions was studied. It was shown that high-energy mixing in hexane leads to the destruction of the crystal structure of Hf and Zr particles and the formation of amorphous composite particles. The synthesized samples of ultra-high temperature ceramics were studied by X-ray phase and microstructure analyzes. It was shown that exothermic synthesis leads to the formation of single-phase solid solutions of HfC and ZrC carbides with the average particle size of 0.2–1.5 μm. The residual porosity of the binary carbides obtained is 10–12 %. It was found that, despite the high temperature of sample heating during ETE under pressure, the particle size of the resulting solid solutions is significantly (by an order of magnitude) smaller than the particle size of similar complex carbides (20–50 μm) obtained by other methods (SPS and hot pressing). This is associated with the rapidity of the exothermic interaction of the reagents (10–50 ms) during ETE.

The combustion of mixtures consisting of titanium powder prepared by SHS hydrogenation and dehydrogenation and black carbon/ boron was studied. It was shown that the oxygen and hydrogen content in Ti powder makes an impact on the combustion characteristics of Ti + C mixtures. It was found that an increase in the hydrogen concentration reduces the combustion temperature, meanwhile, its value is increased with increasing the oxygen content. The mixture with 0.6 wt

The Curie temperature for many structural multicomponent alloys can only be estimated approximately, for example, from state diagrams. The necessity of an operational assessment of this parameter arises in the design of technologies for processing and controlling structural materials, in mathematical modeling of physical processes. The paper describes an experimental method for determining the temperature of magnetic transformation by measuring the temperature dependences of inductance and electrical resistance of wire samples. Verification of the procedure was carried out by determining the Curie temperature of nickel and comparing it with data obtained by other methods. We established the dependence of the Curie temperature of nickel on the carbon content and determined the Curie temperatures for alloys of Fe-Cr and Fe-Ni systems. Using numerical modeling and experimental data, temperature dependences of the relative magnetic permeability of materials were obtained. The results show the presence of the Hopkinson effect in the materials under study and the presence of inflection points on the electrical resistance curves.

Mathematical modeling is applied to study the electrothermal explosion conditions of a gasless system surrounded by a dielectric medium. It is shown how conductive heat exchange intensity and Joule heating power affect the formation of dimensionless temperature and concentration profiles, the integral depth of transformation, and the reaction front propagation velocity. The stages of ignition and reaction propagation are divided using a criterion that assumes a conversion depth of 0.99 at any point in the sample. The amount of product formed at the ignition stage is determined. It is demonstrated that a large transformation depth is achieved near critical conditions during ignition on the axis of the sample, thereby causing the displacement of the ignition zone from the axis to the surface of the sample.

The relevance of creating specialized computer programs that convert a virtual 3D model of an object into machine code (G-code) for controlling the process of 3D printing products from wire raw materials is substantiated. It is shown that for wire-based additive technologies, a fundamentally important requirement is to ensure the continuity of the surfacing trajectory within one section. A method for determining a continuous surfacing trajectory is proposed, the implementation of which requires two stages: performing a numerical analysis of a two-dimensional region with boundary conditions describing this section; and running a heuristic algorithm for the movement of the surfacing head, in which the direction of movement is selected based on the results of the analysis. The procedure for setting boundary conditions and an algorithm for numerically solving the boundary value problem of determining the field of the “height” function for each section are described. The principles of operation of the heuristic algorithm for selecting the direction of head movement based on the calculated height field and continuous determination of the proximity of adjacent layers and section boundaries are disclosed. An analysis of the algorithm operation is carried out using a section with holes as an example, and the potential of using numerical methods to calculate the change in the temperature field during the surfacing process is shown.

This study shows the need for a common structured approach to designing control systems for electron-beam welding, surfacing, and additive shaping plants. The main controlled parameters of the process are highlighted. The three-level hierarchical structure of the control system is described. The control processes are differentiated taking into account the process requirements for electron-beam treatment processes and the features of the vacuum system, the electron gun, and the positioning system, as well as the system of taking images of the treated area according to the signal of backscattered electrons. The types and quantitative characteristics of the parameters of the signals necessary for running the system are given. It is shown that it is effective to divide the control processes in three groups, depending on the requirements on the rapid response of the actuators, as well as on the need for synchronizing some processes with others over time. The presented differentiation is used to propose a method for selecting technical facilities for each of the mentioned groups. An example is provided of constructing a control system for an electron-beam process plant using hardware components available for purchase.

The influence of the thermal state of process-gun elements and their relative arrangement on electron-optical system operation and the beam parameters is studied that are generated. A thermal-heating model of the cathode assembly of the ELA-60B electron gun is developed. To check the model, an experimental bench is developed on the basis of the ELA-15I electron-beam unit, which allows recording the cathode and gun-body temperature, as well as the cathode heating power. The temperature of the cathode and the gun body in the stationary section are used as verification parameters, as well as the temperature dependences in the area of natural cathode cooling and heating of the gun body. Thermal contacts between the contacting surfaces of the cathode assembly are used as debugging model nodes. Cathode assembly deformations are calculated on the basis of temperature fields. To assess the influence of the deformations, a trajectory analysis is carried out, followed by the construction of a current–voltage characteristic. The real current–voltage characteristic of the ELA-60B electron gun is obtained. As a result of strain analysis, it is found that, when heated, the cathode moves forward relative to the control electrode, moving closer to the anode. The control electrode also lengthens and approaches the anode. The trajectory calculation shows that thermal deformations lead to a change in the operating conditions of an electron-optical lens. The current–voltage characteristic shifts to the right, thereby shifting the gun opening boundary, and the beam crossover drops lower towards the anode, which, in turn, leads to a change in the position of the beam focal plane.

Methods for determining the diameter, focusing distance, and convergence angle of an electron beam used for vacuum electron-beam welding are considered. A technique is proposed for determining the boundaries of the electron flux using a continuous wavelet transform of the transverse integral beam profile of the beam obtained from its image on the residual gas in a vacuum chamber. The method is tested on a reference object, and the error in the linear dimensions of the beam is assessed. Quantitative dependences of the minimum beam diameter and focusing distance on the magnetic-lens current for two types of electron beam process installations are obtained. The features of the energy-density distribution in the region of converging and diverging beams are established. The results obtained make it possible to estimate the beam-power density and can be used to study the effect of process parameters on the shape and dimensions of the weld during electron-beam welding.

Effect of mechanical activation of components and external pressure on the combustion of a heterogeneous Ti + C mixture under SHS compaction is under study. It is shown that the presence of pressure (15 MPa) results in low-rate layered combustion (4–7 cm/s) and the absence of any external pressure causes unsteady combustion at a high burning rate (50–70 cm/s), namely surface-annular combustion and volumetric combustion, both based on convective heat and mass transfer. This paper proposes a mechanism for convective combustion at a high burning rate, based on the ignition of a heterogeneous mixture by a hot impurity gas released in a combustion wave and filtered through layered cracks and other macrodefects in the volume of charge compacts, which form during the pressing of powder mixtures. The mechanical activation of the reaction mixture components reduces the density and strength of the compacts and increases the efficiency of the formation of macrodefects. External pressure has the opposite effect as it prevents crack formation and the propagation of hot impurity gas through cracks. The consolidated samples of titanium carbide with a relative density of up to 95

The paper presents the results of a study on the dense titanium carbide production by SHS compaction. It is shown that the use of a mechanically activated reaction mixture of titanium and carbon black powders makes it possible to obtain titanium carbide samples with a maximum relative density of 95 %. A feature of this research is that the mechanical activation of components and Ti + C mixture stirring were carried out in a ball mill. The study covers the influence of process parameters on the combustion properties and structure of the consolidated titanium carbide. It was found that the high-speed reaction mixture combustion is an essential condition for dense titanium carbide production. It was shown that the burning rate and temperature strongly depend on the size, mass and density of charge compacts. With an increase in the diameter (20–58 mm) and weight (10–70 g) of compacts made of mixtures with activated reagents, the burning rate varied from 10 to 100 cm/s, and the burning temperature varied from 2200 to 3100 °C. An influence of the pre-pressing pressure (applied at the combustion stage) on the burning rate and temperature was shown: the burning rate sharply decreases from 100 to 10 cm/s at pressures between 0 and 10 MPa, and the combustion temperature decreases monotonically from 3000 to 2000 °C at pressures between 0 and 40 MPa. A high-speed combustion mechanism was proposed for the titanium and carbon black reaction mixture where the formation of radial (longitudinal) cracks in compacts pressed from the mechanically activated mixture is an important factor. These cracks ensure the propagation of incandescent impurity gases and the exothermic reaction initiation in the sample volume.

Keywords : Forced SHS compaction, mechanical activation, titanium nickelide, combustion temperature, burning velocity, phase composition

NiTi samples with a density of 6.65 g/cm3 were prepared by forced SHS compaction from Ni + Ti powder mixture in an equiatomic ratio. Synthesized alloy was studied by scanning electron microscopy and X-ray diffraction analysis. It was shown that SHS-compacted sample contain NiTi (B2 + R) in addition to secondary phases: Ti2Ni, Ni4Ti3, and Ni. Electrical resistivity as a function of temperature in the range of 290–1150 K was studied.

The effect of activation energy on phase transformations (transitions) in the W–C system during the synthesis induced by an external heat source was investigated by electrothermal explosion (ETE) under pressure. The ETE technology combines self-propagating high-temperature synthesis (SHS) with additional sample heating by Joule heat – electric current passing through the synthesized mixture, and it makes it possible to determine the chemical reaction rate that is highly susceptible to external impacts such as pressure, concentration, sample shape, any film present on combustion products, etc. The chemical reaction rate, i.e. external source current, may be controlled by changing the activation energy. The study was conducted in the following conditions: temperature Т = 293÷3700 K; carbon concentration of 49.8–50.2 at.%; quasi-static compression at P = 96 MPa; external source voltage and current density V = 10 V, I = 20 МА/m2, respectively; samples 8 mm in diameter weighing 6 g. The Т–τ thermogram of the W–C system was used to determine the following parameters: four stages of the synthesis process, temperatures of special points of phase transformations, temperature boundaries of phases and process activation energy. Thermograms of intermediate states are presented as isothermal plateaus of phase transformations. The analysis of experimental results and the physical representation of the process make it possible to assert that temperature plateau parameters are the effective value of activation energy for synthesis mode maintenance. Each of the 4 W–C mixture synthesis stages is described. Pre-explosion stage I – sample heating in the temperature range of Т = 293÷563К, endothermic reaction, effective activation energy for synthesis mode maintenance Q = 2.96 kJ, and taking into account 1-mole mass Еа = 111.6 kJ/mol. Low-temperature (563–1190 К) stage II – ignition, Q = 5.46 kJ, Еа = 109.2 kJ/mol. High-temperature stage (III) in the range of Т = 1190÷2695К, order–disorder transformation, Q = 14.25 kJ, Еа = 424 kJ/mol. Finally, Stage IV occurs in the range of Т = 2695÷3695К, Q = 14.31 kJ, Еа = 143.2 kJ/mol. It was shown that the limiting stage with the highest activation energy is the melting process.

TiB2–Ti metal–ceramic composites were produced by forced SHS compaction. The influence of superstoichiometric amount of Ti (6–20 wt