A technique to fabricate high-entropy alloys by consolidation of powder obtained by joint electric explosion of wires (EEW) is developed at the moment. However, the fabricated alloys exhibit some disadvantages like presence of several phases, heterogeneous element distribution and porosity. The aim of the present work was investigation of possibility to improve the microstructure and phase composition of the near-surface layer of high-entropy AlCrFeCuNi alloy fabricated by EEW followed by consolidation and annealing using irradiation by low-energy high-current pulsed electron beam (LEHCEB) with the surface energy density of 5 and 10 J/cm2. Using X-ray diffraction, transmission and scanning electron microscopy, energy-dispersive X-ray and EBSD analysis, it was found that drops of crystallized melt form on the surface as a result of LEHCEB processing due to release of aluminum oxide on the surface which was not wetted by the alloy melt. It was shown that the drops were single-phase, elements were distributed homogeneously in them, and there were no pores or cracks in the drops. The grain size of drops was several micrometers. It was concluded that LEHCEB processing would be promising for microstructure modification and possible improvement of properties of AlCrFeCuNi high-entropy alloys fabricated by EEW followed by consolidation and annealing, if the problem of aluminum oxide removal from the surface were solved.

Intermetallic matrix composites are promising materials for use in friction units at high temperatures. We applied processing of Ni3Al-10 vol.% TiC composite with 10 or 30 pulses of low-energy high-current electron beam (LEHCEB) irradiation to improve its friction behavior and wear resistance at elevated temperatures. The surface energy density was 8 J/cm2 and accelerating voltage was 30 kV. A wavy relief forms on the surface and significant refinement of Ni3Al matrix grains and TiC particles occurs as a result of LEHCEB processing. Friction tests reveal that the coefficient of friction decreases when the test temperature increases from 600 to 750 °C, and LEHCEB processing variously effects on the coefficient of friction in the latter case. These changes are related to the variation in the composition and structure of the oxide layer. It is found that LEHCEB irradiation under appropriate conditions enables increase in resistance to wear at 600 and 750 °C. SEM analysis of worn surfaces and cross-sections reveals involvement of oxide wear, abrasive wear and wear due to plastic deformation to the overall wear at 600 °C while oxide wear and adhesive wear at 750 °C. Abrasive wear is related to the accumulation and release of debris in dimples of the relief; variation in the contribution of wear due to plastic deformation are caused by hardness increase after LEHCEB processing; adhesive wear is affected by material hardness and by oxide wear rate. The main microstructural features causing variation of hardness and oxide wear rate are refinement of Ni3Al matrix grain size, decrease of TiC particle size down to several tens of nanometers and uniform distribution of nanoparticles in the near-surface modified layer.

Using scanning and transmission electron microscopy, X-ray diffraction, profilometry, indentation and friction tests we investigated the microstructure and phase composition formation in the near-surface layer, microhardness, surface roughness, resistance to cracking and wear resistance in Ni3Al intermetallic compound and "Ni3Al base - thin powder TiC coating" system processed with low-energy high-current electron beam (LEHCEB). We revealed the crucial role of TiC particles in different behavior of these materials under LEHCEB irradiation with the surface energy density of 8 J/cm(2), accelerating voltage of 30 kV and 10 pulses. The mass fraction of TiC in the near-surface was as much as 22 wt % after three times surfacing. It was found that the presence of TiC thin layer enabled essential microstructure and phase refinement in the near-surface layer of the surface composites and improvement in microhardness and wear resistance. The density of surface cracks in the surface composites is 1.8 lower with respect to TiC-free Ni3Al and the roughness keeps the same. The advantages of LEHCEB processing of intermetallic compounds with thin powder layers are attractive for possible practical application.

The Zr-1%Nb alloy is widely used as a structural material for nuclear fuel assemblies of light water reactors. One of its key properties is the behavior upon a possible loss-of-coolant accident (LOCA) that can be changed by the surface modification procedures. This paper presents the research results on the effects of both high-intense pulsed ion beam (HIPIB) irradiation and high-current pulsed electron beam (HCPEB) processing on the kinetics of its oxidation at 1200 degrees C in air and steam, similar to the LOCA conditions. HIPIB irradiation led to more uniform reliefs on the sample surfaces but did not change their phase composition. However, both a and c lattice parameters decreased slightly with a simultaneous increase in microstrains. After HCPEB processing, the general patterns of changes in the modified surface layers were similar, but microcracks were found in some areas. In all studied cases, weight gains were greater after oxidation in air than those in steam. Nevertheless, diffusion of oxygen and the formation of scales occurred more slowly in the modified surface layers due to their distorted crystal lattices. The main reason for the variations was different physical processes that had occurred when the surfaces had been modified with charged ions and electrons.

Using scanning electron microscopy and roughness measurements we studied the relief appeared on the surface of TiC-free Ni3Al and Ni3Al-TiC composites (TiC content was 10 and 30 vol%) as a result of low-energy high -current electron beam irradiation (the surface energy density was in the interval of 8-18.0 J/cm2, the accelerating voltage was 30 kV, the pulse duration was 3.2 mu s, the number of pulses was 10 and 30). Using the same materials differing in the content of non-metallic particles for investigation enabled clarification of the role of non-metallic inclusions in the relief formation. The effect of the particles size, surface energy density and number of pulses was also analyzed. Three types of dimples forming the relief were revealed. Each of the type appeared following to its own formation mechanism. The applicability of the models existing in literature to explain relief formation was discussed.

Using scanning and transmission electron microscopy, X-ray diffraction, indentation and bending tests we studied the evolution of microstructure, phase composition and mechanical properties of TiC-free Ni3Al and Ni3Al-TiC composites (TiC content was 10 and 30 vol%) fabricated by self-propagating high-temperature synthesis (SHS) under pressure induced by low-energy high-current pulsed electron beam (LEHCEB) irradiation with the surface energy density of 8, 12 and 18 J/cm2. It was found that the irradiation results in the improvement of phase composition of the near-surface layer by way of the increase of yield of SHS reaction. LEHCEB irradiation enables formation of nanocomposite structure in the near-surface layer of Ni3Al-TiC composites with decreased grain size of Ni3Al matrix, refined TiC particles and increased volume fraction of TiC. This structure leads to the increase of microhardness but decrease of strength under bending. Two mechanisms of TiC particles refining are suggested. The effect of surface energy density on the manifestation degree of the found phenomena is discussed. The contribution of different hardening mechanisms to the overall hardening is considered.

The effect of low‐energy high‐current electron beam (LEHCEB) irradiation on the microstructure and nanohardness of Inconel 718 alloy produced by laser powder bed fusion additive manufacturing is investigated. The LEHCEB irradiation is applied to the alloy at three energy levels, and the resulting microstructural analysis of irradiated surfaces is conducted. The findings from this study demonstrate that the LEHCEB irradiation substantially changes the as‐built microstructure showing intragranular dendrites of different shapes and irregular‐shaped Laves phases. The columnar structure is formed in the modified near‐surface layer as a result of rapid heating and cooling during LEHCEB irradiation. Furthermore, all Laves phases dissolve in the modified layer. Nanoindentation hardness of the irradiated layer of the alloy increases from 593 ± 23 to 693 ± 13 Hv with the highest energy density of 15 J cm−2. This increment is attributed mainly to the dissolution of Laves phases and the formation of an ultrafine columnar structure where the columns are separated from each other by the district regions containing very thin interlayers of a secondary phase and a high amount of dislocations.

The present study showcases a novel effective technique for the surface modification of micro-arc diatomite coatings using low-energy, high-current electron beams (LEHCEBs). A variety of methods such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, the X-ray diffraction method, scratch testing, the potentiodynamic polarization method, immersion testing in SBF, and flow cytometry have been used to study the coatings. During processing, the electron beams’ energy density ranged between 2.5–7.5 J/cm2. After the LEHCEB treatment, the surface morphology of the coatings changed completely. The corrosion resistance of the LEHCEB-treated coated samples increased significantly, as evidenced by the decrease in corrosion current to 4.6 × 10−10 A·cm−2 and the increase in polarization resistance to 1.4 × 108 Ω·cm2. The electron beam treatment also increased the adhesion strength of the coatings to the magnesium substrate by 1.8–2.5 times compared to untreated coatings. Additionally, biological studies have shown the high viability of the NIH/3T3 cell line after contact with the samples of the coating extracts.

The current research deals with the urgent task of creating highly efficient photocatalysts for wastewater treatment from various organic pollutants. For these purposes, we carried out a mechanochemical synthesis, heat treatment, and study of a non-toxic, thermally and chemically stable catalysts with a heterostructure based on Fe2TiO5 pseudobrookite. The morphology and the properties of the as-prepared composites were characterized through different techniques. The chemical reactions occurring during the step-by-step heat treatment of the samples were proposed using info from XRD analysis, IR spectroscopy, thermal analysis, and mass spectra. The influence of the gaseous medium on the phase composition and the degree of crystallinity of materials has been established. The analysis of the elemental composition and morphology of powder particles was carried out at an annealing temperature in the range from 100 to 1000 degrees C in air. The photocatalytic activity of pseudobrookite was studied during the decomposition of the organic dye Rhodamine B, and the mechanism of photocatalysis asso-ciated with the absorption of photons and the formation of an electron-hole pair was considered. It was found that samples thermally treated in nitrogen were demonstrated greater catalytic activity than those treated in air.

Using X-ray diffraction, scanning and transmission electron microscopy we studied the evolution of the morphology, microstructure and phase composition in the near-surface layer of copper covered with thin (2.8 mu m) ZrO2 coating induced by low-energy high-current pulsed electron beam irradiation (the surface energy density was in the interval of 5.0-18.0 J/cm2, the accelerating voltage was 30 kV, the pulse duration was 3.2 mu s, the number of pulses was 10). The variation of adhesion of the coating to substrate was evaluated using scratch testing. The evaporation of the upper part of the coating during irradiation was found and the thickness of the coating nonlinearly decreased with the increase of the energy density. We discussed the reasons for the surface cracking taking into account microstructural changes in the near-surface layer of the material. The irradiation was found to transfer most of monoclinic ZrO2 phase in the as-deposited coating to tetragonal and, possibly, cubic one. The factors influencing the adhesive strength of the coating were revealed and a potential for the increase of adhesion was demonstrated. We showed that irradiation with enhanced surface energy density was required to obtain copper-based composite hardened with zirconia nanoparticles in the near-surface layer. The thickness of the composite layer may be as much as 6 mu m.

Effects of high current pulsed electron beam irradiation (HCPEBI) on the surface microstructure, mechanical properties, room and high temperature tribological behavior of the Ni3Al-15vol%TiC composite were investigated. The HCPEBI process refines the TiC particles down to nano scale and distributes them homogeneously throughout the modified layer. It also decreases grain size of the Ni3Al down to 400 nm. Grain refinement and homogeneous distribution of the TiC nanoparticles by irradiation process increase surface hardness from 538 HV0.025 to about 728 HV0.025. The HCPEBI process increases also the wear resistance of Ni3Al-15vol%TiC composite at both room temperature and elevated temperature of 600 degrees C due to the increasing hardness and roughening the surface of the sample. Adhesive wear was found to be the dominant wear mechanism for both as-received and irradiated samples at room temperature beside with the delamination. At the elevated temperature of 600 degrees C, oxidative wear and delamination of the oxide layers occur as the main wear mechanisms in the as-received sample. In the irradiated sample, on the other hand, wear starts with the abrasive wear with micro-cutting of surface hills of irradiated sample, and continues with oxidative and delamination wear mechanisms. (C) 2021 Elsevier B.V. All rights reserved.

In the present work, the products in the form of vertical walls were made of heat-resistant nickel-based superalloy ZhS32 via the method of electron beam additive technology. Unidirectional printing strategy was applied. The effect of heat input and 3D printing strategy on the macrostructure, dimensions, and morphology of microstructure elements was established. It was shown that the additive product material has a directed macrostructure. The only exclusion was the final layer with a thickness of no more than 3.5 mm. The directed macrostructure consisted of dendrites oriented predominantly along the crystallographic direction {001} of the primary dendrite arms. The misorientation of the dendrite axes did not exceed 9 degrees. The angle between the predominant dendrite growth direction and the normal to the substrate was 23 degrees. The average primary dendrite arms’ spacing increased monotonically from 16 µm at 5 mm from the substrate to 23 µm in the final layers of the product material (the overall height was 41 mm). It was found that the average size of γ’ (Ni3Al)-phase precipitations in the form of nanoscale and submicrocrystalline cuboids varied in the range of 76 to 163 nm depending on the distance from the substrate. The size of γ’-phase precipitations reached a maximum at about 30 mm from the substrate, while in the final layers of the product material, the average cuboid size did not exceed 135 nm. Extreme dependence of the size of γ’-phase precipitations on the height of the product followed from a combination of a given monotonic decrease in heat input and heat accumulation in the product material as it formed, as did additional heat removal by means of radiation during formation of the final layer of the product without re-melting. Chemical elements of the austenitic steel substrate material were not detected in the product material more than 8 mm from the substrate. There were no macrodefects, such as voids, in the entire volume of the product material.

The aim of the work was investigation of the effect of high current pulsed electron beam irradiation (HCPEBI) with the energy density E-s = 18 J/cm(2), 20 pulses on the surface roughness, microstructure, phase composition and micmhardness of the near-surface layer of aluminum bronze coating deposited on aluminum alloy using cold spray. Using SEM, line and 3D profilometry it was shown that HCPEBI in the used regime enabled smoothing of relief roughness of similar to 50 mu m in height. The content of free volume in the layer essentially decreased: there was very low number of small pores instead of big voids and delamination along the particles interfaces. Using XRD and TEM, formation of the ordered beta(1)' martensite of Cu3Al compound after HCPEBI was revealed. The microhardness of the layer decreased from 5.1 down to 2.2 GPa due to disappearance of the deformation-induced defects and phase transformation.

For the first time, by the example of an AlCrFeCuNi alloy this research work shows the possibility of obtaining multicomponent metal nanoparticles using joint electrical explosion of wires made of different metals/alloys. The analysis of the structural-phase state of nanoparticles has shown that particles have lognormal distribution by size, and their number average size is 40 nm. The nanocrystalline structure of nanoparticles is represented by two phases based on BCC and FCC lattices. According to the research findings, joint electrical explosion of wires made of different metals and alloys is a promising technique for obtaining multicomponent metal nanoparticles.

The paper reports the effect of high-current pulsed electron beam (HCPEB) processing of the Zr-1%Nb alloy as one of the most widely used in water-cooled nuclear reactors, based on the kinetics of its oxidation at 1,200°C in air and steam (these conditions are typical for potential loss-of-coolant accidents). It was shown that HCPEB processing caused a change in the surface morphology of the samples. In particular, craters with diameters of about 100 μm were found on the modified surfaces. They had initiated at an energy density of 5 J/cm2 and were characterized by relevant reliefs with microcracks. After HCPEB processing at 10 J/cm2, the craters were deeper with fractured surface layers. In addition, a pronounced surface relief corresponding to quenched martensitic microstructures was observed on the modified sample surfaces that had formed due to high heating and cooling rates. Due to sufficient degradation of the sample surfaces after HCPEB processing at 10 J/cm2, the kinetics of high-temperature oxidation was estimated only for the as-received samples and ones treated at 5 J/cm2. It was found that the as-received samples showed slightly greater weight gain levels in both air and steam environments, which fully correlated with the thickness ratio of the oxide, α-Zr(O), and prior-β layers. These phenomena and further research directions were discussed.

We report on an investigation of the structure and mechanical properties under quasi-static and planar impact loading of Al-based nanocomposites reinforced with alumina nanoparticles of ball, plate and sheet shape fabricated through accumulative roll bonding (ARB) for 4 and 10 cycles. The distribution of the nanoparticles and structural characteristics of the matrix were revealed using transmission electron microscopy. The micro hardness, ultimate and yield strengths and ductility under tension at the strain rate of 1 x 10(-3) s(-1) were measured as mechanical characteristics under the quasi-static loading. The maximum pressure of the impact compression, Hugoniot elastic limit and spall strength were calculated using the free surface velocity data recorded during the impact by aluminum flyer-plates with the impact velocity of 630 +/- 30 m/s. Our results show that nanoparticles tend to agglomeration inside the composite. The size of agglomerates depends on the nano particle shape and a number of ARB cycles. Only the part of the ball-shaped nanoparticles can be distributed uniformly as separate nanoparticles after 10 ARB cycles. The introduction of the nanoparticles into aluminum assists in the structural refinement in the nanocomposites relative to alumina-free aluminum. This effect is mostly exhibited in the composite reinforced with the ball-shaped nanoparticles, some of which are distributed separately. The nanoparticle of different shape affects the mechanical properties ambivalently under both quasi-static and shock-wave conditions due to their various distribution in the matrix and different properties of the agglomerates. The spall strength decreases with the nanoparticle introduction because the particles and their agglomerates are the stress concentrators and crack origins.

In this study, AM60 magnesium alloy surface modification was performed by electron beam irradiation at different energy densities of 3, 5, and 8 J/cm2 and a pulse duration of 2-4 μs for RITM installation and 100 μs for SOLO installation. Then the surface characteristics were analyzed and the process parameters were optimized based on microscopic images with scanning electron microscopy. The element magnesium, the intermetallic phase of Al-Mn and Mg-Al (Mg17Al12) were observed on the microstructure of all samples. It is significant that due to oxidation, the MgO phase was observed in AM60 alloy which was removed by pulsed electron beam irradiation (PEBI). This technique generally caused the percentage of the AlMn phase to be lower than the raw sample and even at the energy level of 8 j/cm2, the AlMn phase was ignored. However, the percentage of Mg17Al12 phase increased significantly after PEBI and this phase changed from block to point mode and spread throughout the material. It was found that with PEBI the surface characteristic changes and among the three levels of 33, 5, and 8 J/cm2, 5 J/cm2 has the lowest number of cracks and the shortest crack length.

Using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) we studied the distribution of structural parameters, phase composition and alloying elements concentration across the coatings obtained by cladding of chromium and titanium carbides mixture on low-carbon steel. The beam of relativistic energy electrons extracted into the atmosphere was used to form the coatings. The homogeneity in the allying elements distribution is shown to be defined by the lifetime of the melt bath while the phase composition distribution depends on the thickness of the melt layer. Both above parameters are determined by the density of the entered energy.