Carbon fibers are used in the production of automobiles, airplanes, sporting goods, energy, and biomedicine due to their unique properties such as high specific strength, high specific stiffness, low coefficient of thermal expansion, and low density. The research and development of both the technology of carbon-fiber production and their modification for a wide range of applications have been and remain relevant. The summary of accumulated experience in the modification of carbon fibers shows that ion-beam processing allows a variety of geometries of the developed surface topography, in particular, whisker-shaped and corrugated, oriented across or along the fiber, to be obtained. Such processing compares favorably with the usual whiskering of fibers both in terms of the variety of geometries of the composite interface, and by the absence of the problem of whisker-fiber adhesion. Ion-beam processing also makes it possible to modify the surface-layer structure from amorphized to ordered with different degrees of graphitization. Irradiation with chemically active ions leads to the functionalization of carbon fibers due to the formation, for example, of nitrides and carbon oxides. The choice of nitrogen ions for the technology of carbon-carbon and carbon-ceramic composites seems to be more preferable due to less stringent requirements for the temperature of the irradiated fiber. For the ion-beam corrugation of the surface of a polyacrylonitrile-based carbon fiber, only its heating above the temperature of dynamic annealing of the radiation damage is required. The use of helium ions in technological plasma-acceleration systems leads to a significant increase in the efficiency of ion-beam processing.

The modification of carbon–carbon composite materials under high fluence (>3 × 10 18 cm –2 ) irradiation with Не + , Ne + , Ar + , and С + ions with energies of 10–30 keV at irradiation temperatures from room temperature to 600°C has been studied experimentally. It is shown that irradiation of carbon fibers with the ion energies of tens of kiloelectronvolts allows simulating radiation damage in graphites with levels of radiation damage up to several hundred displacements per atom (dpa) and simultaneously studying the effect of ion irradiation at different angles of incidence on plasma-facing materials of fusion plants. The irradiation with helium ions is appropriate for simulation of radiation damage under mechanical stress conditions which include both compression and extension. Irradiation with heavier ions of noble gases (Ne, Ar) is applicable to simulation of mechanical compression stresses. The temperature dependences of the ion-induced electron emission reflect the surface texture of graphite materials and can be used as a method of in situ control of the fiber shell texture.

The results of an experimental study of the effect of high-fluence ion irradiation on the thermal stability of the microstructure and surface relief of submicrocrystalline nickel are presented and discussed. The submicron structure of nickel is obtained during severe plastic deformation by torsion under a high pressure of 6 GPa. Irradiation with 30-keV argon ions with a dose of 3 × 1018 cm–2 is carried out. The ion irradiation of submicrocrystalline nickel is shown to lead to the formation of a cone-shaped surface morphology. This morphology is thermally stable up to a temperature of at least 500°C. Using etching with a focused 30‑keV gallium-ion beam, a surface layer 10-µm thick of irradiated submicrocrystalline nickel annealed at 500°С is studied. It is found that the ion-induced cone-shaped morphology of the surface could be preserved during annealing and block grain growth in the surface layer.

Surface structure modification of PAN based carbon fibers under 30 keV C+, N+, N-2(+) and Ar (+) ions irradiation have been experimentally studied. It has been found that the corrugation effect of the fiber surface, which is typical for high-fluence irradiation with noble gases and nitrogen ions, does not manifest itself under irradiation with carbon ions. The dependences of the formation of surface patterns on depth distributions nu(x) of the number of displacements per atom (dpa) are considered. It has been shown that during corrugation the nu decreases monotonically with a maximum at the surface. The cause of corrugation is twinning of fiber-shell crystallites, which is caused by depth-dependent radiation-induced dimensional changes and relaxation of resulting mechanical stresses. The reason for the absence of surface corrugation under C+ irradiation can be the formation of a textureless modified layer.

We present the results of studying the erosion and ion-induced electron emission of nickel samples with nano-, micro-, and coarse-crystalline structures under high-fluence irradiation with 30-keV argon ions. The nanostructure is formed using high-pressure torsion deformation. The irradiation of nanostructured nickel led to the formation of cones on its surface at a high density, 1 cone/μm2. A decrease in the size of crystal grains to 100 nm and the presence or absence of cones do not affect the coefficient of ion-induced electron emission. The coefficient of the ion-induced electron emission of nickel decreases with an increase in temperature from room temperature to 100–150°C, reaching a plateau up to 400°C. The temperature dependence of the ion-induced electron emission coefficient for nickel can be due to the phonon scattering of secondary electrons.

The results of the effect of high-fluence irradiation (fluence ~3 × 1018 cm–2) with 30-keV C+ ions at a temperature of 250°C on the structure and surface morphology of polyacrylonitrile-based carbon fibers reinforcing the composite KUP-VM are presented and discussed. Scanning electron microscopy shows that the irradiation of carbon fibers with their own ions does not lead, as in the cases of irradiation with ions of inert gases and nitrogen, to corrugation of the fiber surface. The roughness of the composite surface remains comparable to the nonirradiated sample. According to Raman-spectroscopy data, irradiation with carbon ions at temperatures above that of dynamic annealing of radiation-induced damage leads to the formation of a disordered graphite-like layer, as in the cases of irradiation with inert-gas ions. The lack of corrugation of the carbon-fiber surface under irradiation with carbon ions is associated with the lack of a gradient of radiation-induced damage in the modified layer and a texture characteristic of a carbon-fiber shell based on polyacrylonitrile.

The results of a research on the surface morphology of nanostructured nickel after high-fluence irradiation with 30 keV argon ions have been presented. The nanostructure in nickel was formed by high-pressure torsion deformation. It has been shown that nanostructuring deformation of nickel by ion-beam sputtering allows to receive a uniformly coated surface with submicron cones. The thermal stability of the obtained cone-like structure on nanostructured nickel has been determined.

The results of a research on the surface morphology of nanostructured nickel after high-fluence irradiation with 30 keV argon ions have been presented. The nanostructure in nickel was formed by high-pressure torsion deformation. It has been shown that deformation nanostructuring of nickel and subsequent ion-beam sputtering allows receiving a surface uniformly coated with submicron cones. The thermal stability of the obtained cone-shaped structure on nanostructured nickel has been determined. Keywords: nanostructure, high-pressure torsion, ion irradiation, cones, thermal stability.

The modification of the surface of highly oriented pyrolytic graphite (HOPG) under 10, 20 and 30 keV Ar + ions irradiation with fluence 10 18 cm −2 at the irradiation temperature of 250°C has been studied experimentally. An anomalous growth of the ion-induced surface relief of HOPG have been found. This effect, like the well-known effect of anomalous deep embedded argon ions in HOPG, is analyzed within the framework of plastic deformation mechanisms in graphite.

We perform submicron corrugation of the surface of nongraphitized (processing temperature 1400°C) and graphitized (processing temperature 2800°C) Zoltek PX35 polyacrylonitrile carbon fibers by high-fluence irradiation with nitrogen and argon ions with an energy of 30 keV. The microgeometry of the surfaces of nongraphitized and graphitized carbon fibers irradiated with nitrogen ions is characterized by the presence of corrugations with different periods and heights at the same inclination of their faces. The similarity and difference in the microstructure of the surface layer of carbon fiber after heat treatment and ion irradiation, observed by Raman spectroscopy data, are analyzed and discussed. The data obtained suggest an increase in the tensile strength of the modified carbon-fiber layer with a decrease in the elastic modulus. The reasons and conditions for the corrugation of carbon fibers during their ion irradiation are discussed.

Surface patterns on PAN based carbon fibers under 3 and 30 keV He+ and 30 keV Ar+ ions irradiation were experimentally studied. It has been found that the depth distributions v(x) of the number of displacements per atom (dpa) have a strong effect on the surface patterns on PAN-based carbon fibers. For not steady state profiles v(x), a ridge-like structure oriented along the fibers is formed on the surface. At sufficiently high irradiation fluences with a steady-state profile v(x), a corrugated structure is formed with corrugations transverse to the fiber axis. The corrugation effect is explained by twinning during plastic deformation of fiber shell crystallites caused by radiation-induced dimensional changes and mechanical stresses.

A comparison is made of the ion-induced corrugation of the shell of carbon fibers reinforcing a KUP-VM composite upon high-fluence irradiation with $${\text{N}}_{2}^{ + }$$ and Ar+ ions with an energies of 10 to 30 keV at temperatures ranging from 100 to 600°C. Irradiation with noble gas ions is better for simulation of the neutron irradiation of graphite materials. Irradiation with nitrogen ions is preferable when modifying a carbon fiber surface.

The graphitization and surface growth of synthetic diamonds by high-fluence irradiation with 30 keV argon and carbon ions have been experimentally studied. scanning electron microscope (SEM) and atomic force microscope (AFM) show removal of traces of mechanical polishing. The ion-induced roughness does not exceed 20 nm. Raman spectroscopy and the measurement of electrical conductivity confirm the graphitization of the surface layer when irradiated with argon ions at the temperature of 230 °C and the diamond structure of the synthesized layer when irradiated with carbon ions at the temperature of 650 °C.

The ion induced modification of the structure and morphology of low-temperature (SU-1300) and high-temperature (SU-2500) glassy carbons after high-fluence (>= 10(18) cm(-2)) irradiation with 30 keV Ar+ ion in the temperature range from 60 to 600 degrees C are presented and discussed. Raman spectra show an amorphized state of surface both for the low and high-temperature glassy carbons at an irradiation temperature below the temperature of the dynamic annealing of radiation damage, determined by the temperature dependence of the ion-induced electron emission yield; a graphite-like structure at 140 <= T <= 350 degrees C for SU-1300 and at 140 <= T <= 250 degrees C for SU-2500; a structure similar to non-irradiated low-temperature glassy carbon at 350 < T <= 600 degrees C and 250 < T <= 600 degrees C for low- and high-temperature glassy carbons, respectively. In both cases, ion irradiation leads to the temperature-dependent changes in the topography of the modified layer. Ion irradiation under conditions of the dynamic annealing of radiation damage leads to a network topography of the nanowalls.

The results of experimental study of the surface nano-and microstructuring of polyacrilonitrile (PAN) based carbon fiber VMN-4 and viscose based carbon cloth TGN-2MK under 30 keV Ar+ irradiation are presented. Scanning electron microscopy shows a strong difference in evolution of ion-induced morphology for these two carbon fiber types. At sufficiently high fluences, a corrugated morphology is formed on the PAN based carbon fiber, while a network of nanowalls is formed on the viscose based carbon fiber. The found differences are associated with a significant effect of the structure of the surface layer of carbon fiber on ion-induced dimensional changes.

The results of experimental study of the irradiation under 30 keV Ar+ with the temperature ∼250 °C of viscose based carbon cloth TGN-2MK and SU-2500 glassy carbon are presented. According to the scanning electron microscopy and Raman spectroscopy, modified layer of TGN-2MK obtained by ion irradiation is similar of modified layer of the glassy carbon in the structure and morphology. The formation of nanoscale wall in both cases occurs during graphitization under conditions of dynamic annealing of radiation damage.