Fundamental’nye problemy sovremennogo materialovedenia / Basic Problems of Material Science

THE EFFECT OF CF4 PLASMA TREATMENT ON THE WETTABILITY OF CARBON FIBER-REINFORCED PLASTIC SURFACE

Efim Neustroev — 2025-12-25

The article investigates the effect of inductively coupled CF₄ plasma on the wettability of carbon fiber-reinforced plastic surfaces. Plasma treatment was performed using a plasma power of 200 W and a CF₄ gas flow rate of 100 cm³/min. The treatment duration ranged from 5 to 40 minutes. The surface elemental composition was analyzed using X-ray energy-dispersive spectroscopy. The surface morphology was examined using electron microscopy and atomic force microscopy. Raman spectra, photoluminescence intensity, and contact wetting angles were also studied. After 20 minutes of treatment, the fluorine content on the surface reached 27 at.%, with only a slight increase observed when the treatment time was extended to 40 minutes. A change in the state of the carbon fiber surface from hydrophilic to hydrophobic was detected as a result of plasma exposure. Contact angle measurements following plasma treatment showed an increase of 60–65° compared to the initial values. A direct relationship between the duration of plasma exposure and the wetting angle is shown. The maximum contact angle of 135° was achieved after 40 minutes of treatment. The observed effect is attributed to a reduction in surface energy due to the formation of C–F bonds during plasma fluorination. An additional contribution to the enhanced hydrophobicity is provided by changes in surface morphology caused by plasma etching. In this case, the hydrophobic behavior of the surface can be theoretically described by the Cassie–Baxter model and/or its modification proposed by Marmur.

A REVIEW OF RESEARCH ON ANALYSIS, TESTING, AND MACHINE LEARNING OF INTERATOMIC POTENTIALS USING DELOCALIZED NONLINEAR VIBRATIONAL MODES

Igor Kosarev — 2025-12-25

Molecular dynamics (MD) is a powerful tool for materials research, allowing one to work with millions or more atoms. However, in molecular dynamics, the quality of the interatomic potential is crucial. To analyze and test a wide range of potentials, we propose using delocalized nonlinear vibrational modes (DNVMs). DNVMs are exact solutions to the equation of atomic motion obtained based on the symmetry of the structure and, unlike analysis based solely on phonon modes, allow vibrations over a wide range of amplitudes and include both the linear (phonon) and nonlinear parts of the vibration. This approach allows testing potentials from both linear and nonlinear physics perspectives. Therefore, this paper presents a review of two studies investigating DNVMs in BCC tungsten. One of them compares existing potentials with respect to ab initio data, while the other already presents a machine-trained potential using DNVM and shows the difference in DNVM reproducibility over a wide range of amplitudes.

FORMATION OF ATOMIC ORDERING DURING HEATING AND ANNEALING OF NiAl3 ALLOY

Evgenii Lakman — 2025-12-25

Intermetallic compounds of the Ni-Al system, formed in the aluminum-rich region of the phase diagram, namely NiAl₃ and Ni₂Al₃, remain poorly understood. The limitations of experimental and theoretical studies of these compounds include their complex crystallographic structure and relatively low melting points. In this paper, molecular dynamics simulation was used to study the formation of the atomic structure during heating and annealing of the NiAl₃ intermetallic compound with the D0₁₁ superstructure. The computational cell consisted of 16000 atoms. Interatomic interactions were defined using the embedded atom potential approximation developed by Mishin et al. An analysis of the atomic distribution in the crystal was performed using the Cowley short-range order parameter and X-ray diffraction. The Cowley parameter values are estimated for several coordination spheres at different temperatures, allowing one to observe changes in atomic ordering with increasing temperature. X-ray diffraction line profiles were constructed during heating and annealing. Satisfactory agreement between the interplanar spacings calculated for virtual diffraction patterns and experimental values is demonstrated.

COMPUTER SIMULATION OF THE ELECTRONIC STRUCTURE AND REACTIVITY OF MODIFIED C60Xn FULLERENES (n = 2, 4, 6) USING THE CONCEPTUAL DENSITY FUNC-TIONAL THEORY

Andrey Ryabykh — 2025-12-25

A comprehensive computer simulation of a series of C₆₀ fullerene derivatives modified with two, four and six identical functional groups X of different nature (X = -CH₃, -C₂H₅, -C₃H₇, -F, -Cl, -Br, -OH, -OCH₃, -OC₂H₅, -SH, -SCH₃, -SC₂H₅, -NH₂, -NO₂, -COOH, -COCl, -CONH₂, -CN) was performed. The aim of the work was to establish the dependencies between the structure of molecules and their key electronic and reaction descriptors. The calculations were performed using the ORCA 6.1 and Multiwfn 3.8 software packages within the framework of the density functional theory (DFT) using the PBE0-D4 hybrid functional and the def2-SVP (structure optimization) and def2-TZVPD (electron and reaction descriptor calculation) basis sets. Within the framework of the conceptual DFT, the chemical potential μ, hardness η, electrophilicity ω, nucleophilicity N, ionization energies I and electron affinities A were analyzed. For the first time, relative scales of electronic chemical potential <δμ> and hardness <η> were proposed for these systems, allowing to classify the groups by the strength and direction of their influence on the donor-acceptor properties of fullerene structures. A cumulative increase in the influence of substituents upon transition from di- to tetra-derivatives and a deviation from linearity for hexa-substituted structures caused by steric effects were found. It was established that bulky groups with heteroatoms (S, O, N) can become new reaction centers. The results of the work allow one to predict the redox activity and related properties of modified fullerenes and are the basis for targeted design of structures with specified properties.

FEATURES OF HEAT TRANSFER IN CARBON DIAMOND-LIKE THIN FILMS

Vladimir Plotnikov — 2025-12-25

Abstract
It is believed that the thermal conductivity of non-metallic materials, including diamonds, is carried out mainly by phonons. However, the situation is more complicated in carbon diamond-like films. It would seem that in single-phase diamond films the phonon mechanism of thermal conductivity is obvious. However, the multiplicity of interfaces and the presence of a high concentration of hydrogen reduce the thermal conductivity coefficient to 0.2 - 3.0 W / (mK) in diamond films, that is, by three to four orders of magnitude compared to the thermal conductivity of a diamond single crystal. Only in micron diamond films does the thermal conductivity coefficient approach the thermal conductivity of a diamond single crystal. The complexity of substantiating the mechanism of thermal conductivity in carbon thin (nanometer) films lies in the features of the structure, which is actually a thin-film composite of diamond-like and graphite-like clusters, the size of which is 0.5 - 1.0 nm. Thus, such a composite is a set of regions with different mechanisms of thermal conductivity - in diamond-like clusters, the phonon mechanism operates, in graphite-like clusters, the electronic mechanism of heat transfer prevails. That is, at the interface, a change in heat transfer from phonon to electronic is observed. However, in carbon diamond-like films, there are no interfaces, diamond-like and graphite-like clusters are linked by sp3- and sp2-bonds, which is accompanied by the appearance of localized electronic states in the forbidden zone of the diamond-like cluster until it is completely filled. In fact, the diamond-like cluster becomes an electrically conductive cluster. This effect significantly complicates the mechanism of thermal conductivity.

COMPOSITE BIOCOMPATIBLE MATERIALS BASED ON CHITOSAN AND CALCIUM PHOSPHATES FOR BONE RECONSTRUCTION

Rustam Sadykov — 2025-12-25

Bone implant materials play a significant role in modern biomedical materials science due to the increasing incidence of bone diseases. Calcium phosphate-based biocomposites are one of the promising materials in this field. However, these materials in their pure form have a number of drawbacks, such as insufficient biological activity, which opens up the possibility of modifying calcium phosphate cements with polymeric materials that can improve the physicochemical and biological properties of these materials. Thus, in this work, a composite material based on brushite/chitosan and hydroxyapatite/chitosan with a chitosan mass content of 0.05 wt.%; 0.2 wt.%; 0.4 wt.% was synthesized. The phase and component compositions were determined by X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy (FTIR). The morphology and structure of the composites were characterized using scanning electron microscopy (SEM). The contact angle and surface energy were measured using the sessile drop method. Solubility was assessed by incubating samples in saline followed by titration. Biocompatibility was tested using human monocytes

MOLECULAR DYNAMICS MODELING OF THE EFFECT OF VACANCY CONCENTRATION ON THE MECHANICAL PROPERTIES OF CNT-REINFORCED α-TI UNDER UNIAXIAL TENSION

Ustina Yankovskaya — 2025-12-25

The aim of this study was to conduct a comparative analysis of the influence of point defect (vacancy) concentration and carbon nanotube (CNT) reinforcement on the deformation behavior and mechanical properties of a titanium single crystal under uniaxial tension. The study was performed using the molecular dynamics method in the LAMMPS software package. For all models, uniaxial stretching was performed with a constant strain rate at a temperature of 300 K. Key mechanical characteristics were determined: tensile strength, yield strength, and Young's modulus. A non-monotonic effect of vacancies on the strength of α-Ti has been established. It has been shown that a vacancy concentration of 0.5% leads to dispersion strengthening of the matrix (ultimate strength = 14.75 GPa, for a defect-free crystal = 14.43 GPa). The introduction of CNTs stabilizes the ultimate strength at a level of ~12 GPa for all vacancy concentrations, leveling their influence. It was found that the Young's modulus of the composite increases with an increase in the proportion of vacancies (up to 103.13 GPa at 1.0%), which indicates the dominant role of CNTs in elastic deformation. It was found that the composite destruction occurs by the mechanism of interphase delamination at the interface, which leads to a decrease in the yield strength. For models with embedded CNT, the key factor determining the mechanical properties of the composite is the strength of the matrix-CNT interface.

THERMOPHYSICAL CHARACTERISTICS OF LANTHANUM, PRASEODYMIUM AND EVOLUATION OF THERMAL PROPERTIES OF THEIR ALLOYS USING THE RULE OF MIXTURE OF COMPONENTS

Sergey Terekhov — 2025-12-25

Despite the widespread practical use of rare earth metals, there is almost no information in the scientific literature about the thermal physical properties of earth metals and their alloys. Existing thermodynamic models have both advantages and disadvantages, but none of them describe the behavior of the thermal properties of earth metals in the temperature range of the condensed state using a single continuous function. In this regard, a new approach to the theoretical representation of real systems was proposed. In the frame-work of the studied model, calculations were made for the thermal physical characteristics of lanthanum and praseodymium, such as heat capacity, thermal linear expansion coefficient, density, thermal conductivity, temperature conductivity, and specific electrical resistance. The obtained temperature dependencies adequately describe the experimental data. Using the rule of mixing components, estimates of the thermal properties of several lanthanum alloys with praseodymium have been obtained. The thermal properties of the alloys are limited by the corresponding characteristics of lanthanum and praseodymium. During the calculations, the effect of inheritance of a number of characteristics in the temperature curves of the components by the alloys was confirmed. However, it has been suggested that a more rigorous calculation could lead to the neutralization of this effect and the emergence of new collective phase transitions and structures as a result of the mixing of interacting components.

EVALUATION OF SPECIMEN SLIPPAGE UNDER HIGH PRESSURE TORSION USING NOTCHES AND MARKERS

Dmitry Gunderov — 2025-12-25

The paper considers the effect of slippage under high-pressure torsion (HPT) of Grade-4 titanium specimens using conventional marker application techniques and a cutout in the specimen. At the initial stage of HPT (striker rotation angle j_t = 36°), the slippage estimated from the marker shift was L = 35%. A cutout was made in the Ti specimen after preliminary HPT nS»2,5, into j_t = 54°. The shift of the copper insert body was significantly less than expected, and over the main volume of the specimen, the slippage was L = 96%. However, in the upper right corner of the copper insert, a copper “tongue” of about 15 μm thick, captured during torsion, is clearly visible, spreading over the Ti surface. This may indicate that during HPT, the flow occurs predominantly in the local “striker-sample surface” contact zone. It can be assumed that the localization of the slip on the surface distorts the results of the slip assessment by the "method of applying markers to the surface of the samples before HPT". This explains the difference in the slip value recorded by the marker on the surface and by the "method of cutting in the sample" (or "method of joint HPT of two disk halves").

CHANGES IN THE MECHANICAL PROPERTIES OF AL-10SI-MG ALLOY SAMPLES UNDER THE INFLUENCE OF A PULSED MAGNETIC FIELD OBTAINED USING SELECTIVE LASER SINTERING

Ekaterina Nosova — 2025-12-25

The relevance of the study is related to ensuring the mechanical properties of aluminum alloy samples obtained by selective laser fusion. Plates with a thickness of about 1 mm were obtained from Al-10Si-Mg (RS300) powder aluminum alloy, and magnetic pulse treatment with a current strength of 11...21 kA was performed. The assumption has been experimentally confirmed that whirl currents of several tens of kiloampers are induced in samples under the influence of impulse magnet field, causing uneven heat generation across the sample material due to a higher level of electrical resistance along the grain boundary. That leads to an instantaneous local release of heat, which can lead to micro-melting of the material along the boundaries of metal powder composition’ particles. This can probably lead to a change in the metal bonds between the particles, which in general should lead to an increase in the mechanical properties of the product. Uniaxial tensile test, microhardness measurements and metallographic studies were performed, which showed a change in the grain boundary structure and an increase in the mechanical properties of the material by 20-30%. The directions of further research have been determined to explain the changes in mechanical properties after exposure to an aluminum alloy by a pulsed magnetic field.

MODIFICATION SURFACE OF HEAT-RESISTANT VH9L CASTING ALLOY BY LASER PULSE OXIDATION IN AIR

Igor Rodionov — 2025-12-25

Experimental studies of the process of laser thermal treatment of the surface of the heat-resistant casting alloy VН9L in the mode of pulsed radiation generation have been carried out. By means of laser pulse scanning oxide coatings with thickness of 20-30 μm with microhardness of 8-11 GPa are obtained. Using raster electron microscopy, the structure of the formed thermal oxides was studied depending on the power of pulsed radiation. A kinetic model of laser oxidation of metals in the composition of the VН9L alloy in air was built by the mechanism of surface nucleation. By increasing the laser power from 150 W to 200 W, the degree of oxidation of the metal surface decreases from 26% to 12% due to an increase in the metal temperature and the tendency of the formed oxide to decompose. The calculated values correspond to the obtained experimental data with a critical nucleus size of 0.3 nm, atomic oxygen desorption heat of 350,000 J/mol and a total processing time of 0.02 s. It was found that during laser oxidation of samples from alloy VН9L, the formed oxide phase mainly includes chromium and titanium oxides. The content of iron and nickel oxides in the modified surface composition is insignificant and corresponds to trace micro-quantities. It has been shown that laser pulse oxidation can be used as a promising modification method when producing mechanically strong and corrosion-resistant metal oxide films and coatings on articles.

ON THE APPLICATION OF ULTRASONIC PROCESSING TO POLYMERIC PRINTING COMPOSITES

Marina Perlina — 2026-01-16

The development of modern technologies leads to the active introduction of new effective solutions in industrial production, including the use of polymer composite materials. These materials are distinguished by a combination of various components that provide unique physical and mechanical properties, such as resistance to external factors, high temperature and mechanical stress. Polymer composites are used in various fields of industry due to their ability to adapt to specific operating conditions. The importance of choosing the right binder is emphasized by the need to take into account the variety of fracture mechanisms and carry out tests that correspond to the actual operating conditions of the products. Modern modification of polymer matrices with the help of chemical additives and special physical effects helps to improve the performance characteristics of materials. Special attention is paid to the development of environmentally friendly and cost-effective solutions that meet the needs of industrial production, including printing production, where resistant and safe paint and varnish materials and adhesives are in demand.