In this work, the peculiarities of microstructure changes in Cr-coated Zr1%Nb alloy under high-temperature hydrogenation and Kr ion irradiation were investigated. A comprehensive analysis revealed that Cr coating reduces the thickness of the Kr+ radiation damage zone by 15%–20% and decreases the density of radiation-induced defects compared to that of uncoated Zr1%Nb alloy. Additionally, Cr-coated samples exhibit a more uniform hydrogen distribution. According to first-principles calculations and positron annihilation spectroscopy, hydrogen-free dislocations predominate in the Cr-coated Zr1%Nb alloy after hydrogenation and irradiation. These findings emphasize the protective role of Cr coatings in mitigating radiation damage and hydrogen embrittlement in zirconium alloys.

As the development of nuclear fusion depends on plasma-facing materials, new methods for improving the radiation resistance of tungsten are being created and tested. This paper presents the results of studying the structure, surface morphology, phase composition, and residual internal stresses in tungsten alloys modified by plasma flows and irradiated with helium ions with an energy of 40 keV and doses of (1–3) × 1017 cm−2. It is shown that the effect of compression plasma flows on tungsten leads to the modification of its grain structure in the near-surface layer, forming dispersed cells of 220–320 nm in size due to high-speed crystallization. The results of measuring the lattice parameters and internal stresses in irradiated tungsten alloys showed that the near-surface layer accumulates radiation defects, creating internal stresses, the relaxation of which leads to local destruction of the surface. Preliminary plasma treatment creates an increased density of intergranular boundaries, which serve as sinks for radiation defects and increase the radiation resistance of tungsten alloys.

ZrN, (Zr,Ti)N, (Zr,Hf)N, (Zr,Nb)N, (Ti,Zr,Hf)N, and (Ti,Zr,Nb)N coatings mechanical and corrosion properties were investigated in this work. Coatings were deposited by vacuum arc deposition technique on Ti-6Al-4V titanium alloy. Microhardness measurements, tribological and scratch tests, profilometry, electrochemical corrosion tests, and scanning electron microscopy were used as investigation techniques. The highest microhardness value (36.2 GPa) was observed for the (Zr,Hf,Ti)N coating, and the lowest value (12 GPa) for the (Zr,Nb)N coating. The highest critical forces Lc3 during scratch tests were found for coatings containing hafnium. It was revealed that the shape of anodic potential dependence on time during electrochemical corrosion tests in galvanostatic mode (3% NaCl environment) was strongly dependent on coating type. The time necessary to reach the maximum stable value of anodic potential can be an indirect parameter of corrosion resistance. (Zr,Nb,Ti)N coating demonstrated the best corrosion resistance in used test regimes.

The MAX phase (Ti2AlN) was synthesized by reaction sintering of Ti, TiN, Al precursors in vacuum in quartz ampoules. The effect of temperature on the formation of the Ti2AlN phase was estimated. The MAX phase with a minimum amount of impurities was obtained at 1300 degrees C. The elemental and phase composition and structure of the synthesized samples were studied. According to the X-ray diffraction analysis, the obtained samples, along with the main phase Ti2AlN, contain impurity phases TiN, TiAl, Ti3Al. The results of electron microscopy show heterogeneity of the elemental composition of precursor particles, which differ in size and morphology. In well-formed crystallites of the MAX phase with a layered structure, the Ti/Al/N element ratio is close to the stoichiometric composition of Ti2AlN. The quality of the layered structure of Ti2AlN and the simplicity of the synthesis technique make the material promising for some applications, in particular, for obtaining 2D MXene (Ti2N) particles.

The changes in internal stresses and mechanical properties of V‑Nb-Ta-Ti alloys manufactured by arc melting after irradiation with He2+ ions (40 keV) to a fluence of 2 ⋅ 1017 cm−2 are studied. The irradiation of V, VNb, and VNbTa alloys is shown to decrease the compressive macrostresses in the pre-peak region and increase them for V and VNbTa in the peak region of helium implantation. The irradiation of a VNbTaTi high-entropy alloy increases the compressive macrostresses by 44

Cobalt nanotubes have been synthesized by electrochemical deposition in pores of ion track membranes. The structures obtained have been studied by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, and gas permeability method. The influence of electron irradiation on the cobalt nanotube structure has been investigated. It is shown that an increase in the irradiation dose leads to the transformation of the sample crystal structure. This fact can be explained by the simultaneous reduction of the β-Co metastable phase and relaxation of the microstress formed by the fcc phase in the lattice. The degree of sample texturing along the [100] direction increases under electron irradiation. The dependences of the resistive and magnetic properties of cobalt nanotubes on the irradiation dose have been analyzed.

Investigation of compression plasma flows impact on structure, phase, and elemental composition, as well as mechanical properties of Ti-6Al-4V titanium alloy with ZrN coating was carried out in this work. X-ray diffraction, scanning electron microscopy, energy dispersion X-ray analysis, samples weight measurements, microhardness and tribological tests were used as investigation techniques. The findings showed that plasma impact led to the formation of a composite surface layer based on tita- nium alloy containing inclusions of undissolved ZrN coating. Growth of the absorbed energy density resulted in a decrease of zirconium and nitrogen concentration in the surface layer due to erosion. Formation of solid solutions on the basis of alpha-Ti and beta-Ti was found in the layer analyzed by X-ray diffraction. Presence of nitrogen in a vacuum chamber as plasma generating gas led to the formation of TiN on the surface. Plasma impact resulted in decrease of ZrN/Ti-6Al-4V system microhardness and decrease of friction coefficient (at specific treatment regimes).

The article presents the comprehensive analysis results of the connection between structural changes caused by the effects of deformation swelling and softening effects during high-dose irradiation with He2+ ions, alongside determines the kinetics of changes in structural and strength parameters contingent upon irradiation conditions (in the case of irradiation temperature variations). The interest in such studies is due to the need to study the influence of temperature factors on the diffusion mechanisms of implanted He2+ into the damaged layer of a high-entropy TiTaNbV alloy in the case of high-dose irradiation. At the same time, the study of such mechanisms makes it possible to determine not only the radiation resistance of TiTaNbV alloys, but also to expand the general understanding of the influence of the structural features of high-entropy alloys associated with deformation distortion of the crystal structure, which prevents diffusion and migration mechanisms of defect propagation in the damaged layer. During determination of changes in strength properties depending on irradiation conditions, it was found that irradiation temperature growth leads to both a rise in the degree of softening under high-dose irradiation and an increase in the thickness of the softened layer under high-dose irradiation. These changes indicate that at high temperatures, the diffusion of implanted ions is not restrained by structural distortions, which results in their migration to a greater depth exceeding the ion travel depth, which should be considered when designing the use of these alloys in the case of their operation in extreme conditions.

To clarify the efficiency of irradiation resistance, investigation of body-centered cubic concentrated HfNbTiZr and dilute V-4Cr-4Ti alloys, irradiated by 40 keV He ions up to 5 x 10(16), 1 x 10(17) and 5 x 10(17) cm(-2) fluences at room temperature, was carried out. Similar to V-4Cr-4Ti, HfNbTiZr possesses high phase stability and surface erosion resistance to irradiation with He ions up to 5 x 10(17) cm(-2) . Using transmission electron microscopy, a more than 2-fold increase in overall swelling, as well as its intensification with increasing fluence was observed for HfNbTiZr compared to V-4Cr-4Ti. Combining atomistic calculations and simulations based on the Modified Embedded Atom Method interatomic potential and Density Functional Theory, the energetics of defects and helium-vacancy complexes, as well as their dynamics, were studied for alloys. It was shown that in the HfNbTiZr and dilute vanadium alloys the number of radiation-induced vacancies (v) can be comparable. According to the binding energy curves, there is a tendency for higher He accumulation in helium-vacancy complexes due to the increased He/v ratio in HfNbTiZr compared to V-4Cr-4Ti (similar to 1.5 versus similar to 1.1). It was found that the kick-out of lattice atoms is enhanced in HfNbTiZr and is suppressed in V-4Cr-4Ti. Therefore, the more intense He bubble growth in HfNbTiZr may be due to the kick-out mechanism, which leads to a decrease in the He/v ratio and stimulates helium-vacancy complexes to trap additional He atoms. Our results can be used to improve the bubble swelling resistance in the design of new multicomponent concentrated alloys.

The results of studying the influence of high-energy pulsed plasma treatment on the kinetics of zirconium oxidation are presented. Samples of commercial pure zirconium alloy are treated with compression plasma flows in the mode of melting of the surface layer, which results in the formation of a dispersed grain structure and growth of the zirconium-nitride surface layer. Subsequent annealing in air at temperatures of 700 and 900°С lead to the formation of a monoclinic phase of zirconium dioxide ZrO2 with a small amount of the tetragonal (high-temperature) modification. Preliminary plasma exposure is shown to contribute to an increase in the volume fraction of the tetragonal phase due to its stabilization by internal stresses due to a high defect concentration. Plasma pre-treatment also reduces the rate of zirconium oxidation.

A good Ti-based joint implant should prevent stress shielding and achieve good bioactivity and anti-infection performance. To meet these requirements, the low-elastic-modulus alloy—Ti–35Nb–2Ta–3Zr—was used as the substrate, and functional coatings that contained bioceramics and Ag ions were prepared for coating on TiO2 nanotubes (diameter: (80±20) nm and (150±40) nm) using anodization, deposition, and spin-coating methods. The effects of the bioceramics (nano-β-tricalcium phosphate, microhydroxyapatite (micro-HA), and meso-CaSiO3) and Ag nanoparticles (size: (50±20) nm) on the antibacterial activity and the tribocorrosion, corrosion, and early in vitro osteogenic behaviors of the nanotubes were investigated. The tribocorrosion and corrosion results showed that the wear rate and corrosive rate were highly dependent on the features of the nanotube surface. Micro-HA showed great wear resistance with a wear rate of (1.26±0.06)×10−3 mm3/(N·m) due to adhesive and abrasive wear. Meso-CaSiO3 showed enhanced cell adhesion, proliferation, and alkaline phosphatase activity. The coatings that contained nano-Ag exhibited good antibacterial activity with an antibacterial rate of ≥89.5

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.

Bulk materials, pure Ni, CoCrFeNi, and CoCrFeMnNi, were deposited by arc melting with subsequent cold-rolling till 85% thickness reduction and annealing at 1150 degrees C. They were irradiated by 40 keV He2+ and 280 keV Kr14+ low-energy ions to the fluences of 2 x 10(17) cm(-2) and 5 x 10(15) cm(-2), respectively. Estimation of the distortions in the alloys was by calculating the normalized distortion parameter, which tends to increase with the increment of alloy complexity and atomic radii mismatch. x-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis showed a common superiority of CoCrFeNi over pure Ni in radiation resistance (less lattice deformation, no blistering). In both Ni and CoCrFeNi after ion irradiation, signs of tension microstress remained positive and the magnitudes showed similar responses, CoCrFeMnNi microstresses became compressive-negative; the dislocation density also showed decrease after Kr-irradiation compared with non-irradiation. Mn addition to the ternary alloy changed its behavior radically. Normalized distortion parameter calculation can be performed for quick simple comparative theoretical analysis comparison of the radiation resistance, but will not give full information about the difference between stoichiometries investigated.

Investigation of compression plasma flows impact on surface relief of Ti-6Al-4V titanium alloy was carried out in this work. Profilometry, x-ray diffraction, scanning electron microscopy, and sample weight measurements were used as investigation techniques. The findings showed that plasma impact led to the formation of developed surface relief (Ra parameter was changed in the range of 0.7-2.7 μm) due to the action of hydrodynamic instabilities at the melt-plasma border. Increase in the number of pulses resulted in the growth of Ra value. Numerical simulation of surface evolution under plasma impact was carried out on the basis of the model of incompressible fluid potential flow. Simulation data correlated with experimental data set. The hydrodynamic flow of the melt during plasma impact led to another process: surface erosion. Increase in both the absorbed energy density and the number of pulses resulted in erosion intensity increase. Formation of titanium nitride on the surface was observed as a result of the interaction of nitrogen (as a plasma generating gas) with the surface heated under plasma impact. Titanium nitride film prevented the development of the surface relief formed by the action of hydrodynamic instabilities.

This work studied the effect of sequential irradiation by krypton and helium ions at room temperature on the composition and structure of CoCrFeNi and CoCrFeMnNi high-entropy alloys (HEAs). Irradiation of the HEAs by 280 keV Kr14+ ions up to a fluence of 5 × 1015 cm–2 and 40 keV He2+ ions up to a fluence of 2 × 1017 cm–2 did not alter their elemental distribution and constituent phases. Blisters formed on the nickel surface after sequential irradiation, where large blisters had an average diameter of 3.8 μm. The lattice parameter of the (Co, Cr, Fe and Ni) and (Co, Cr, Fe, Mn and Ni) solid solutions increased by 0.17% and 0.37% after sequential irradiation, respectively. Irradiation by Kr ions led to a decrease in tensile macrostresses in the HEAs in the region of krypton ion implantation (Region I) and the formation of compressive macrostresses in the region behind the peak of implanted krypton (Region II). Sequential irradiation formed large compressive stresses in Ni and HEAs equal to −131.5 MPa, −300 MPa and −613.5 MPa in Ni, CoCrFeNi and CoCrFeMnNi, respectively, in the Region II. Irradiation by krypton ions decreased the dislocation density by 1.6–2.3 times, and irradiation with helium ions increased it by 11–15 times relative to unirradiated samples for CoCrFeNi and CoCrFeMnNi, respectively. Sequentially irradiated CoCrFeMnNi HEA had higher macrostresses and dislocation density than CoCrFeNi.

In this paper we report the synthesis and characterization of the boron-enriched pyrolytic carbon (B-PyC). In the research we aimed to propose a material demonstrating high strength characteristics and heat resistance, durability, chemical inertness and biocompatibility. The material has been synthesized by high temperature low pressure CVD method. The synthesis is carried out on the inner surface of a vertically oriented hollow graphite hexagonal prism heated to the temperatures 1450-1570 degrees C. Controlled low-density flows of nitrogen, boron trichloride and carbonaceous gas react in this zone producing B-PyC film deposited on the vertical graphite plates. Morphology, mechanical and physical properties of this material was investigated using X-ray diffraction, scanning and transmission electron microscopy, mechanical testing instrumentations, thermogravimetric and thermal analysis. It was found that during the synthesis a two-phase crystalline system is organized comprising fragments of graphene layers (pyrolytic carbon) and boron carbide B4C. Such a structure provides high mechanical properties of the material and their stability in a wide temperature range, heat resistance, chemical inertia and biocompatibility. Depending on the synthesis conditions, the micro hardness may vary in a wide range including the range 100-140 HV the most attractive for traumatology and cardiac surgery as well as for a variety of engineering applications.

High-entropy alloys (HEA) are promising structural materials that will successfully resist high-temperature irradiation with helium ions and radiation-induced swelling in new generations of nuclear reactors. In this paper, changes in the elemental and phase composition, surface morphology, and structure of CoCrFeNi and CoCrFeMnNi HEAs irradiated with He2+ ions at a temperature of 700 °C were studied. Structural studies were mainly conducted using the X-ray diffraction method. The formation of a porous surface structure with many microchannels (open blisters) was observed. The average diameter of the blisters in CoCrFeMnNi is around 1.3 times smaller than in CoCrFeNi. It was shown that HEAs’ elemental and phase compositions are stable under high-temperature irradiation. It was revealed that, in the region of the peak of implanted helium, high-temperature irradiation leads to the growth of tensile macrostresses in CoCrFeNi by 3.6 times and the formation of compressive macrostresses (−143 MPa) in CoCrFeMnNi; microstresses in the HEAs increase by 2.4 times; and the dislocation density value increases by 4.3 and 7.5 times for CoCrFeNi and CoCrFeMnNi, respectively. The formation of compressive macrostresses and a higher value of dislocation density indicate that the CoCrFeMnNi HEA tends to have greater radiation resistance compared to CoCrFeNi.

In the original publication [...].

In this study, radiation-induced segregation was studied in high-entropy alloys (HEA) CoCrFeNi, CoCrFeMnNi, irradiated with helium ions He2+ with an energy of 40 keV at room temperature. Changes in the concentrations of HEAs and their depth distributions were studied by Rutherford Backscattering (RBS) and energy dispersive x-ray spectroscopy (EDS) methods. Measurements using the RBS and EDS methods showed that non-irradiated HEAs have a composition close to equiatomic, where the average concentration for CoCrFeNi is 24.8 atomic percents (at.%), and for CoCrFeMnNi – 20 at.%. The EDS results were significantly different from the RBS in Ni/Co concentrations, and indicated no significant changes in element distribution in both HEAs after irradiation. According to the RBS data, the largest changes in concentrations during irradiation in both HEAs relate to the enrichment of Ni atoms. In CoCrFeNi, upon irradiation, Ni/Co atoms undergo the greatest segregation, and in CoCrFeMnNi, the Ni/Co/Fe concentrations change significantly. In CoCrFeMnNi, the change in element concentrations with increasing irradiation fluence was more pronounced than in CoCrFeNi. In CoCrFeMnNi, changes in concentrations of all elements at both fluences reached 0.5–17% (0.1–3.1 at.%) and exceeded changes in CoCrFeNi, which reached 2–11% (0.5–1.9 at.%). It was found that the resistance to segregation when irradiated with helium ions under these conditions was lower for CoCrFeMnNi than for CoCrFeNi. In CoCrFeNi and CoCrFeMnNi, changes in the concentrations of Co, Fe, Cr, and Mn were significantly less than changes near sinks and defect clusters when irradiated with nickel ions with similar doses in other studies at temperatures close to the halfmelting temperature of nickel HEAs. The RBS study showed a uniform distribution of atoms in depth and resistance to segregation in CoCrFeNi, CoCrFeMnNi when irradiated with helium ions.

This paper reports the results of the studies addressing the production of a high-entropy carbide of a TiZrNbHfTaC5 composition, followed by its consolidation and Bi ion irradiation at room temperature. The mechanical and thermophysical properties of consolidated samples are analyzed before and after irradiation. Their X-ray diffractometry is performed, and the crystal lattice parameters and microstress values are determined by the Williamson–Hall (W-H) method.