The aim of this study was to analyze the phase composition of metal films formed by plasma-assisted vacuum arc deposition due to evaporation of a near-equiatomic TiNbZrTaHf cathode. High-temporal- resolution data were obtained by an in situ X-ray diffraction analysis using synchrotron radiation. The use of this technique made it possible to identify the time interval of formation of the films and that of change in their phase composition. It was revealed that the film growth occurred in three stages. At the first stage of film deposition, (3 phase (bcc lattice, a = 0.34748 nm) was identified. At the second stage, an amorphous-crystalline phase formed, as evidenced by the rise in the background of the diffraction line in the angular range of 2 theta = 24-25 deg. At the third, final stage, the diffraction lines of omega phase (hexagonal lattice; a = 0.46636 nm and c = 0.27872 nm) and alpha phase (hcp lattice; a = 0.31261 nm and c = 0.47846 nm) were detected. After completion of the deposition process, the films contained 84 wt.% (3 phase, 14 wt.% alpha phase, and 2 wt.% omega phase.

Titanium dioxide coatings have been formed by vacuum-arc plasma-assisted method and their structure, phase composition and properties have been studied in detail. It is shown that the discharge current of the gas plasma source is one of the key parameters allowing to control the polymorphic composition of titanium dioxide coating, its hardness and wear resistance. Titanium dioxide in coatings is present in two polymorphic modifications: rutile and anatase, the relative content of which depends on the conditions of plasma assist. Titanium dioxide coatings, irrespective of the plasma assisted mode, are nanocrystalline material having a columnar structure.

The formation of nitride coatings based on the titanium (Ti), niobium (Nb), zirconium (Zr), tantalum (Ta), and hafnium (Hf) (i.e., TiNbZrTaHf) high-entropy alloy (HEA) was studied by in situ X-ray diffraction analysis using synchrotron radiation. HEA-based nitride coatings were formed as thin films (1.5-2 mu m) by plasma-assisted vacuum arc deposition. The multielement gas-metal plasma used was produced by evaporating a near-equiatomic TiNbZrTaHf cathode. In studying the thin film growth in situ with high time resolution, the VEPP-3 electron storage ring was used as a synchrotron radiation source. To verify the data of the in situ X-ray diffraction analysis, electron diffraction spectra of the films were obtained using transmission electron microscopy. It was found that the film growth was a multistage and multiphase process. The deposition of a metallic sublayer on the substrate before coating deposition (the first stage of film synthesis) was accompanied by the formation of a three-phase system represented by beta, alpha, and omega metallic phases, which were in an amorphous-crystalline state. The nitride layer formed on the metal substrate was presented by metal-nitride (MeN) and MeN* phases, which differed in the type of crystal lattice. The diffraction lines of the nitride phases were blurred, which might have been due to the nanocrystalline state (0.7-1.2 nm) of the film.

An experimental and theoretical study is carried out to control the distribution of electron beam current density in a SOLO source with a plasma cathode based on a low-pressure arc discharge with grid stabilization of the emission plasma boundary. It has been shown experimentally and numerically that using a control electrode in the form of a disk (disks) in the plasma cathode and a leading magnetic field, it is possible to change the distribution of the emission current density and, accordingly, the energy density of the electron beam on the collector. Theoretical study using the envelope method, “particle-in-cells” method and drift-diffusion models shows good agreement with experiment.

The paper proposes the reduction of the surface roughness and improvement of its strength properties for metallic materials and products fabricated by additive manufacturing. The proposed technique implies the creation of a 2 µm thick metal film on the doped surface layer by the vacuum arc deposition and pulsed electron-beam processing of the film/substrate system. The proposed technique of the film (Zr)/substrate (VT6) system processing provides a 25 times reduction of the surface roughness and improves its strength properties by 1.5 times.

We consider some new and recently modernized vacuum ion-plasma electrophysical facilities used to create dense low-temperature plasma in considerable volumes (≥0.25 m3), as well as a complex unit that includes beam and plasma modules for various processes of electron-ion-plasma modification of the surface of materials and products to improve their functional properties. The paper also provides the examples of modification processes using the developed equipment, as well as the results on improving the properties of modified surfaces.

In a source with a plasma grid cathode based on a low-pressure arc with layer stabilization of the emission plasma boundary, a method of combined control of the electron beam current during a submillisecond pulse of its generation has been developed. A diagram of power supplies and their connection to the electrodes of the electron source is presented, as well as oscillograms demonstrating the possibility of an extended range of control of the power of the electron beam by changing the concentration of the emission plasma by adjusting the discharge current, with a simultaneous change in the width of the ion layer at the surface of the emission grid due to grid control when applying a potential bias to an additional grid electrode. Expanding the power range of the generated beam opens up new opportunities for the use of electron sources of this class for both scientific and industrial purposes.

Using the example of an electron source with a plasma cathode based on a low-pressure arc discharge with grid stabilization of the cathode/emission plasma boundary and an open anode/beam plasma boundary, a mechanism is described for increasing the electrical strength of a high-voltage accelerating gap by introducing a series negative current feedback (NCF) in the accelerating interval, which makes it possible to level out uncontrolled bursts of the beam current during its pulse. The introduction of NCF is achieved by using a special electrode in the space of the plasma emitter connected through a resistance to the anode of the arc discharge, and the main task of which is to intercept accelerated ions penetrating into the emitter from the high-voltage accelerating gap, due to which the current of electron emission from the arc discharge plasma decreases by a value proportional to the ion current in the accelerating gap. Since most sources and accelerators of electrons with plasma cathodes based on discharges of various types have a similar principle of operation, the use of this method will not only expand the limiting parameters of the generated electron beams, but also increase the stability of the operation of such electron sources, and, accordingly, beam irradiation of various materials and products.

Some physical principles and design solutions that were used in the creation and modernization of electron sources with grid plasma emitters and which made it possible to improve their parameters and operational properties are considered. As an example, the main characteristics of modernized low-energy (up to 25 keV), medium-energy (up to 100 keV) and relatively high-energy (up to 200 keV) electron sources with grid plasma emitters are given, which are distinguished by a unique set of basic parameters, which allows them to be used both in scientific, and for technological purposes. The prospects for further development of such sources are shown and the scope of their application is considered.

Thin (3 µm) metal coatings with a columnar nanocrystalline bcc structure composed of crystallites of size 1.5–2.5 nm were formed from a near-equiatomic HfNbTaTiZr cathode through its plasma-assisted vacuum arc evaporation. The hardness of the coatings is 4.7 GPa. Their specific wear rate and friction coefficient measure 1.6 × 10–6 mm3 N–1 m–1 and 0.82, respectively.

In a source based on a non-self-sustaining high-voltage glow discharge with the extraction of a large cross section electron beam (2900 cm2) into the atmosphere, the dynamics of the anode plasma during the generation period of an auxiliary glow wire discharge with a hollow cathode is demonstrated. A repetitively pulsed generation mode with a frequency of 10 kHz was used. The features of the formation and evolution of the auxiliary discharge anode plasma were studied by measuring the distribution of the electron beam current density in the atmosphere. By applying a negative potential bias to the anode grid by (50–200 V) relative to the walls of the vacuum chamber, the possibility of increasing the electron beam extraction coefficient into the atmosphere during the discharge generation pause is shown. New modes of electron beam generation and its more efficient extraction into the atmosphere open new prospects for using electron sources of this type both in science and in industrial applications.

On the example of an electron source with a plasma cathode based on a low-pressure arc discharge with grid stabilization of the cathode/emission plasma boundary and an open anode/beam plasma boundary, a new method of electron beam formation is described, in which an additional auxiliary arc discharge is ignited in the anode region of the source. Initiation of the discharge was carried out by the electron beam, and the discharge itself was supported by an additional power source, which represented a low-impedance artificial forming line included in the collector circuit. The dependence of the current in the accelerating gap on the current flowing in the collector circuit was obtained in the absence of the arc discharge current of the plasma cathode.

The article presents testing results of electron beam processing (EBP) modes applied on the diffusion layers based on boron and aluminum produced on the surface of steel 20. An ion current feedback loop in the accelerating gap in a modernized plasma electron source allows increasing the beam generation control and the electrical strength of the accelerating gap. This ensures sample surface processing at a specified temperature. In order to ensure the EBP process stability, it is proposed to preheat the surface to a temperature range of 400-700℃ by pulses with a controlled current. Further modification of the diffusion layers is conducted on the surface at a temperature of around 1900℃. Ensuring this temperature range demands the discharge current within the range of 20 - 150A during a single pulse with a duration of 950 μs. The total number of pulses is three and the interval between them is 3 seconds. These processing modes lead to a structural transformation of the diffusion layer to a depth of more than 150 μm and to a significant microhardness increase. The approved EBP modes can be recommended as a promising alternate approach of the combined modification technologies of diffusion layers based on boron and aluminum.

We consider the possibility of modifying the adhesive properties of polyethylene films by an electron beam in the atmosphere to produce composite materials. The modification was carried out on a wide-aperture (750 × 150 mm) low-energy (up to 200 keV) electron accelerator DUET with a grid plasma cathode based on a low-pressure arc and the output of a submillisecond beam of large cross-section into the atmosphere. By the method of studying the wetting edge angle, it was determined that the modification of polyethylene films in various radiation intervals improves adhesive properties, and the edge angle was reduced from 101° of the original to 65° of the modified ones. Infrared spectroscopy and scanning electron microscopy revealed the formation of oxygen-containing (C=O, C–O) functional groups and an increase in the relative intensity of the absorption bands, which indicates a chemical change in the structure of the surface of the material, contributing to the improvement of adhesive properties. The method of atomic force microscopy revealed a decrease in the greatest height of profile irregularities from 125 to 40.4 nm, which contributes to an increase in the contact area of the adhesive with the surface. Experiments on modification of polyethylene films by a large-section electron beam with atmospheric discharge confirm the possibility of using installations of this type to improve adhesive properties and create composite materials based on them.

The results of experiments on the generation of a radially converging electron beam in a source with a multiarc grid plasma cathode are presented. The beam was generated at an accelerating voltage of up to 50 kV, a discharge current of 50–300 A, a pulse duration of 50–500 μs, and a pressure of 20–50 mPa. The operation modes of the electron source are compared, and the design of the plasma emitter is modernized to increase the current density to a level sufficient to modify the surface of the collector material.

Al-Si alloys are among the most common aluminium based materials for cast products due to theirhigh strength-to-weight ratio, excellent processability and relatively low cost. The presence of Si inthe molten Al phase improves the castability and decreases the solidification shrinkage. Hard anodicoxidation is largely employed to improve their surface mechanical properties and corrosion resistance.However, the presence of high Si contents (> 3%) and the size of Si particles in the alloy makethe process challenging or even not possible. The surface pretreatment of Al-Si alloys with intensepulsed electron beams (EB) can effectively overcome the aforementioned limitations. Electron beamsources can be employed to reduce Si content and to refine and disperse Si particles, and effectivelycreate an Al substrate that is more prone to oxidization. In the present work, two electron beamunits were used, RITM-SP and SOLO, to modify the surface properties of hypoeutectic, eutectic andhypereutectic Al-Si alloys, by investigating the effect of energy density and number of pulses. Theelectron beam treated substrates were hard anodized and characterized in term of microstructure,elemental distribution, corrosion resistance and surface mechanical properties.

Anodic oxidation is widely employed in industry to impart high mechanical properties and improve the corrosion resistance of Al–Si alloys. However, compared to pure Al, the high content of Si prevents the growth of a uniform anodic layer, leading to the formation of cracks and porosities within the oxide. In the present work, low-energy high-current electron beam is used as pretreatment of a hypoeutectic Al–Si alloy to enhance the properties of the anodic oxide. Electron beam modified samples showed a fine and homogenous dispersion of Si in the α-matrix, together with a content reduction of Si in the treated layer. Hard anodic oxides grown on electron beam pre-treated alloys exhibited a higher microhardness, increased by 65

The results of measuring the current density distribution of a wide-aperture electron beam outputted into the atmosphere and generated in an accelerator based on a non-self-sustaining high-voltage glow discharge (HVGD) are described. A self-sustained glow wire discharge with a hollow cathode was used to generate the emission plasma. A comparison was made of the inhomogeneity of the beam current density in the atmosphere in continuous and pulse-periodic emission generation modes.

Результатом модификации поверхности металлов и сплавов путем комбинированной обработки (напыления тонких металлических пленок с последующим перемешиванием под действием высокоинтенсивных потоков энергии) является формирование градиентной структуры поверхностного слоя материала, характеризующейся изменяющимися по глубине концентрацией легирующих элементов, фазовым составом и состоянием дефектной субструктуры, что положительно сказывается на механических и трибологических свойствах материала. Целью настоящей работы является формирование высокопрочных силицидо- и нитридосодержащих поверхностных слоев при комплексной обработке в едином вакуумном цикле, включающей нанесение покрытий тугоплавкого металла и кремния, облучение высокоинтенсивным импульсным электронным пучком и дополнительное азотирование в плазме газового разряда низкого давления. Модифицирование, сочетающее многоцикловое (до пяти циклов облучения системы «пленка/подложка») высокоскоростное плавления системы «пленка (Si (0.2 мкм) + Nb (0.2 мкм))/(сталь 40Х) подложка» интенсивным импульсным электронным пучком осуществляли на установке «КОМПЛЕКС» (Институт сильноточной электроники СО РАН) в едином вакуумном пространстве. Часть образцов была дополнительно подвергнута азотированию в плазме газового разряда низкого давления (773-873 К, 1-5 час.). Выполнены исследования и выявлен режим комплексного модифицирования, позволивший многократно повысить износостойкость (более чем в 100 раз) и микротвердость (более чем в 5 раза) поверхностного слоя исходной стали. Высказаны предположения о физической природе повышения трибологических и прочностных свойств материала.