A review of studies on the effect of intense flows of argon ions and high-power pulsed laser radiation on properties such as microhardness, radiation erosion, structural changes, corrosion resistance in liquid lithium, and changes in surface topography under conditions of separate and sequential irradiation with Ar+ ions and laser radiation of low-activated vanadium alloys (V–0.59Ga, V–1.86Ga, V–3.49Ga, V–3.4Ga–0.62Si, V–4.51Ga–5.66Cr, and V–4.8Ti–4.82Cr) in comparison with pure vanadium is presented. The samples were irradiated with argon ions in a vacuum in an ILU accelerator at energy of 20 keV, a dose of 1022 m–2, an ion flux density of 6 × 1018 m–2 s–1, and Tirrad 700 K. The parameters of laser irradiation in the GOS 1001 facility in vacuum in the Q-switched mode are as follows: flux power density is q = 1.2 × 1012 W m–2, pulse duration is τ0 = 50 ns, and number of pulses is from 1 to 4. For the first time, we discovered new phenomena such as the possibility of radiation blistering during implantation of heavy ions into metals, the appearance of a long-range effect (two-sided change in microhardness, target structure, and surface morphology), and an increase in the erosion of materials under the successive action of ions and laser radiation on them. Corrosion of both materials irradiated with argon ions and unirradiated materials when tested in liquid lithium at a temperature of 600°C for 400 h is identical (nitrogen penetration into materials is insignificant, and oxygen release from materials is significant, which causes the formation of a zone with reduced microhardness near the surface of the samples).

The effect of high-power pulsed-laser irradiation generated in a GOS 1001 installation in the Q‑switched mode (power density q 1.2 × 1012 W/m2, pulse duration of τ0 = 50 ns, number of pulses N = 1–4) in vacuum on the porous structure of the vanadium sample surface is studied, as well as on its hardness determined in two ways based on the restored-imprint method and on the kinetic indentation method. The porous structure is formed during the implantation of helium ions (energy 30 keV, dose 2.0 × 1023 m–2, ion-flux density 4.8 × 1018 m–2 s–1, temperature 500 K). It is shown that irradiation with helium ions causes vanadium hardening by about a factor of two, and the microhardness values determined by the restored-imprint method are slightly lower than the kinetic hardness values. It is found that a common feature of target destruction under laser radiation, a crater appearance, surrounded by a ridge, behind which there is a zone of thermal influence. Erosion observed in this zone, caused by the destruction of domes of blister bubbles filled with implanted helium and impurity atoms (C, O, N) which are present in the liquid metal. It is found that with an increase in the number of laser pulses, the microhardness in the crater decreases, while the narrow area around it hardens, and with further distance from the crater, the microhardness approaches values corresponding to that of vanadium implanted with helium ions.

Changes in the morphology of the vanadium surface are studied as a result of the separate and sequential action of helium ions (for an energy of 30 keV, a dose of 1.0 × 1022 m–2, an ion-flux density of 4.8 × 1018 m–2 s –1, and a temperature of ~500 K) and high-power pulsed laser radiation in the Q-switched mode (power density of q = 1.2 × 1012 W/m2, pulse duration of τ0 = 50 ns, and a pulse number N varying from 1 to 4). It is found that the effect of laser irradiation on vanadium samples before and after ion implantation (resulting in the formation of a crater with a rim due to the splashing of melted metal) is identical. In the case of the preliminary introduction of helium into the material the splash of metal is more intense. Helium implanted into the samples causes radiation blistering; the subsequent influence of laser pulses intensifies material erosion in the area located immediately behind the rim (resulting in a growing number of peeled layers, merging blisters, etc.), which is probably triggered by high temperatures and thermal stresses emerging in this area (even after discontinuing laser irradiation). Under reactor operating conditions this effect can lead to increased plasma contamination. It is shown that the damage of a target inside the craters in the initial vanadium samples feature occasional cracks, wavy and droplet structures, as well as beading, whereas along with the above changes the samples pre-irradiated with helium contain no cracks inside the crater although areas showing boiling of the material are clearly visible.

ИССЛЕДОВАНИЕ КОМПЛЕКСНОГО ВОЗДЕЙСТВИЯ ИНТЕНСИВНЫХ ПОТОКОВ ИОНОВ АРГОНА И ИМПУЛЬСНОГО ЛАЗЕРНОГО ИЗЛУЧЕНИЯ НА ПОВЕРХНОСТЬ ВАНАДИЯ И СПЛАВОВ НА ЕГО ОСНОВЕ (Обзор)И.В.Боровицкая 1 , С.Н.Коршунов 2 , А.Н.Мансурова 2 , Г

The features of the damage of the surface layer of vanadium under the action of pulsed laser radiation are studied. Laser irradiation is carried out in air using a GOS 1001 setup in the Q-switching mode with the following parameters: flux power density q = 1.2 × 108 W/cm2, pulse duration τ0 = 50 ns, and number of pulses N = 1–6. The typical surface damages induced by the laser pulses are found to include the melting of material, a microcrack network, a wavy relief, and drop-like particles. The central region characterized by the greatest degree of damage contains also individual drops of metal, which crystallized like a spiral. The heat-affected zone (HAZ) adjacent to the central one is damaged to a significantly weaker extent. Surface degradation increases as the number of pulses increases. Laser irradiation is revealed to change the X-ray diffraction (XRD) patterns: loss of texture, presence of vanadium-oxide signal, peak broadening, and lattice parameter increase (from 3.022(2) to 3.027(3) Å). It is shown that preliminary irradiation with argon ions (dose of 1022 m–2, E = 20 keV) affects no surface damage of the central region, while in the adjacent heat-affected zone, there is a spallation of local surface regions.

The microstructures and the porosity parameters in vanadium alloys irradiated by helium ions are compared after preparing thin films from them for transmission electron microscopy (TEM) by two different techniques. V–1% Ti, V–1% Ta, V–2% Ta, and V–1% Ta–1% W alloy samples are subjected to annealing at 1000°C for 2 h and then to 40-keV helium ion irradiation to a fluence of 5 × 1020 m–2 at a temperature of 650°C. TEM samples are prepared by one-sided electrolytic thinning (ET) on the unirradiated side and by focused ion beam (FIB) cutting normal to the irradiated surface. The microstructures of the foil samples prepared by ET and FIB are shown to be significantly different, which leads to a discrepancy between the calculated porosity parameters and the irradiation-induced swelling. When samples are prepared by ET, the picture substantially depends on the material layer to be fixed, and the layer thickness and position are not controlled. Therefore, the use of ET samples leads increases the error of measuring the porosity parameters, and reproducibility of the results can hardly be reached in this case, which should be taken into account in investigations. Using FIB technique, one can measure the foil thickness in a scanning electron microscope during sample preparation, study the total swelling of the entire irradiated layer, and analyze the distribution of objects over the depth of an irradiated target along ion trajectories.

The copper vapor laser (λ=271 nm) “KULON-10Cu-M” was used to modify 32Li2O-26Nb2O5-42SiO2 glass. Morphology of the modified area studied using polarization optical microscopy. Discovered ablation, the refractive index change and crystals haze. μ-Raman spectroscopy for the laser irradiated parts indicates that only a single phase of LiNbO3 is observed.

— The long-range effect that manifests under Ar + ion implantation into vanadium and its alloy V–4.51Ga–5.66Cr is studied experimentally. Irradiation is carried out in an ILU ion-beam accelerator (energy of Ar + ions, 20 keV; dose, 1.0 × 10 22 m –2 ; and fluence, 6 × 10 18 m –2 s –1 ). The target temperature increases during ion-beam bombardment up to ~700 K. It was demonstrated that ion bombardment under the indicated conditions is accompanied by a long-range effect consisting in an increase of the target microhardness, both on the exposed and reverse sides, in double-sided modification of the target’s texture and surface topography. These data are in qualitative agreement with both mechanisms and models proposed to date to explain the observed long-range effects. They are based on the development of a dislocation network in static stress fields that are caused by impurity atoms implanted at high implantation doses and their migration very deep into the bulk of the target.

The results of an investigation of the development of porosity and swelling in the alloys V–Cr, V–W, V–Ta, and V–W–Ta irradiated by 40 keV helium ions to fluence 5·10 20 m – 2 at 650°C are presented. The investigations were conducted by means of transmission electron microscopy along the travel path of ions; this afforded some idea about the total swelling of the samples and the character of the depth distribution of the porosity in the targets. It was found that the gas swelling in binary alloys is identical to within the measurement error. Multicomponent alloying is effective from the standpoint of the suppression of helium swelling – the ternary alloy V–1%W–1%Ta is subjected to significantly less helium swelling. It observed for the first time in experiments that the distribution and penetration depth of helium ions different significantly from the calculations, and the effect depends strongly on the chemical composition of the irradiated alloy. Among the alloying elements tantalum promotes deeper penetration of helium ions. In addition, the effect increases with increasing concentration of tantalum in the alloy: in the alloys V–1%Ta and V–2%Ta, pores were discovered at depth 450–500 and 850–900 nm, respectively, which is significantly greater than the computed travel distance of 48 keV helium ions in vanadium (~300 nm).

The development of helium porosity in vanadium and its alloys with tungsten, zirconium, and tantalum during sequential ion irradiation by 40-keV He + ions at 650°C to a fluence of 5 × 10 20 m –2 and 20-keV H + ions at 20°C to a fluence of 5 × 10 20 m –2 is studied by transmission electron microscopy. The microstructure and the development of porosity in the alloys are investigated along the ion range. Unlike He + ion irradiation, the alloying elements during sequential He + and H + ion irradiation increase the gas swelling of vanadium: tantalum causes the maximum swelling and zirconium minimum one. Gas bubbles in the tantalum-containing alloys are located at the depths that are significantly more than the calculated helium and hydrogen ion ranges. Deep penetration of introduced gas atoms is shown occur mainly along the grain boundaries that are perpendicular to the irradiated surface. The largest bubbles (gas-filled pores) during He + ion irradiation are found to grow at the depth with a high radiation vacancy concentration rather than the maximum helium concentration. In sequential He + and H + ion irradiation, a zone with large pores forms more deeply, in the ion range zone, and large pores in the 100-nm-thick layer transforms into high-density small bubbles.

Carbon films 50–180 nm thick on nickel substrates are fabricated by the ion sputtering of graphite and the deposition of heavy hydrocarbons from the gas phase with simultaneous electron irradiation. Irradiation results in the formation of bonds in carbon films due to the sp and sp3 hybridization of orbitals (sp and sp3 bonds), mainly, sp3 bonds. A fraction of these bonds does not change with growth in the electron energy; it increases three-fold with a reduction in the temperature and an increase in the electron current density. Electron irradiation enhances the film microhardness which exceeds 12 GPa. The films, prepared by heavy hydrocarbon deposition, contain CHn bonds and a small fraction of sp3 bonds. The maximum value of the microhardness of the hydrocarbon films is no more than 4.5 GPa. The analysis of the proposed model of the kinetics of forming different allotropic phases in a carbon film to be deposited shows that a temperature reduction changes the specific volume of an atom in the lattice, while under conditions of simultaneous electron irradiation, it appreciably increases the content of the phase with sp3 bonds. The effect of spi-bond breakage during electron-beam-assisted deposition weakly depends on the electron energy. The weak excitations of electrons of carbon atoms can also result in the formation of sp3 bonds and increases their concentration with growth in the electron current density.

Studies are presented of helium porosity in EP-450 oxide-dispersion-hardened yttrium steel, obtained by electopulse sintering, as a function of the Y2O3 content in comparison with EP-450 matrix steel and dispersion-hardened steel fabricated by hot extrusion. It is found that multiple zones with different types of helium porosity and different zone distribution develop in steel with 1 wt.% Y2O3; in steel with 0.3 wt.% Y2O3, there are fewer such zones than in matrix steel and steel obtained by hot extrusion. It is proposed that the extremely nonuniform distribution of porosity over volume and size in steel fabricated by electropulse sintering is associated with the initially strongly defective structure, including residual porosity, as well as with the chromium redistribution between ferrite grains and tempered-martensite grains during the sample preparation process.

Oxide dispersion strengthened (ODS) ferritic-martensitic steels are considered as promising structural materials for fusion reactors, as well as for active zone of new generations fast reactors. In this connection, peculiarities of helium porosity formation and gaseous swelling have been investigated in the dispersion-strengthened EP-450 ODS steel with 0.3 and 1 wt.% Y2O3 dispersant produced by spark plasma sintering (SPS) as compared with the matrix EP-450 steel, EP-450 ODS steel produced using a hot extrusion (HE) as well as reactor austenitic ChS-68 steel. The samples were irradiated by 40-keV He+ ions at 923 K up to fluence of 5 x 10(20) ion/m(2). Microstructural investigations of irradiated samples were performed using a transmission electron microscope. It is found that plurality of zones with a very different type of helium porosity and different character of their distribution is developed in steel with 1 wt.% Y2O3. Such zones are less in steel with 0.3 wt.% Y2O3 as opposed to matrix EP-450 steel, EP-450 ODS steel obtained by HE, and austenitic ChS-68 reactor steel. It is found in comparing the character of helium porosity formation in the matrix steel EP-450, steel EP-450 ODS (HE) and EP-450 ODS (SPS) that bubbles are developed with a smaller average sizes and, therefore, helium swelling is lower in all ODS steels than that in steel EP-450, but for ODS steel made by SPS, swelling is significantly higher than in ODS steel produced by hot extrusion. At the same time, austenitic steel ChS-68 shows a minimum gaseous swelling for the used conditions of helium ion irradiation. An assumption is made that the extremely non-uniform distribution of helium bubbles (gas filled pores) both in volume and size in SPS steel is associated with the initially highly defect structure, including the residual porosity in 1-3% as well as a result of strong redistribution of chromium between ferritic grains and grains of tempered martensite during manufacturing of samples.

The results of investigation of the effect of chemical composition and structural and phase states of reactor steels and vanadium alloys on their capture and retention of hydrogen introduced into the materials in various ways are presented. It is shown that, in the case of identical conditions of hydrogen introduction, the amount of hydrogen captured by austenitic steels is substantially higher than that captured by ferritic/ martensitic steels. At the same time, the EP450 ODS ferritic/martensitic steel dispersion-strengthened with nanosized yttrium oxide particles retains a substantially higher amount of hydrogen as compared to that retained in the EP450 matrix steel. The alloying of vanadium with tungsten, zirconium, and titanium leads to an increase in the amount of retained hydrogen. The effect of titanium content on hydrogen retention is found to be nonmonotonic; the phenomenon is explained from a physical view point.

Carbon films 110–180 nm thick are fabricated on nickel substrates by the ion sputtering of graphite with simultaneous electron irradiation and subsequent ion irradiation. Irradiation leads to the formation of bonds in the films in various proportions due to the sp and sp 3 hybridization of orbitals ( sp -and sp 3 -bonds). Ion irradiation induces, to a greater extent, the formation of sp bonds, while concurrent electron irradiation increases the portion of sp 3 bonds. Electron and ion irradiation increases the film microhardness which reaches a value of 12 GPa. A model of the kinetics of creating carbon allotropes in a deposited film is proposed, which is based on the competition between the formation and breakage of carbon bonds during hybridization of different types. Electron and ion irradiation influence the probabilities of the formation and breakage of carbon bonds in the deposited film. The model provides a qualitative interpretation of the observed content ratios of carbon phases in the deposited film.