Russian Physics Journal最新文献

The microstructure and mechanical behavior of novel low-activation chromium-manganese austenitic steel in a cold-deformed state are investigated after annealing at 900 °C for 1, 10, and 100 h. It has been shown that at short annealing times (1 h), dispersed M₂₃C₆ carbide particles (M—Cr, Mn, Fe) precipitate at grain and microtwin boundaries. Increasing the annealing time to 10 h leads to the onset of detwinning processes. After 100 h of annealing, significant reduction in the density of deformation-induced microtwins and dissolution of thin carbide plates occur. The carbide particles at the boundaries and within grains coagulate. A decrease in the density of deformation microtwins contributes to the corresponding decrease in the strength and an increase in the plastic properties of the steel after annealing. Despite a significant reduction of the yield and tensile strength after high-temperature annealing compared to the cold-deformed state, they have comparable or higher values than in the quenched state, which indicates high thermal stability of the steel microstructure.

The paper investigates the properties of wear-resistant coatings based on TiAlN, TiAlC, and TiAlO systems. The coatings are produced by cathodic arc deposition onto substrates made of VK8 hard alloy. Coatings are deposited by using different gas mixtures in a vacuum chamber and different rotation speed of the worktable. The microhardness and thickness of the deposited coatings are then measured, and scratch and tribology tests are conducted.

The influence of superstoichiometric Pb and Sn with concentrations up to 1.0 at.% on the electroconductivity σ and thermoelectric coefficient α of PbTe and SnTe crystals has been investigated within T ~ 90–300 K. It is revealed that significant effects of excess Pb/Sn on σ and α are observed for annealed samples, and this effect weakens with an increase in the cation vacancy concentration in the sample. The obtained data are explained by the acceptor effect of the cation vacancies, partial filling of these vacancies with excess Pb/Sn atoms, and the donor effect of Pb and Sn in these crystals as well.

This study presents a neural network model for automatic defect detection and localization in terahertz images of manufactured components. The model employs an architecture based on MBConv blocks and achieves mean IoU values of 0.93 and 0.72 for two defect types, respectively. To eliminate the class imbalance, a 15-fold cross-validation with a weighted loss of the cross entropy is used. Training was performed using the AdamW optimizer with OneCycleLR scheduling and BF16 precision. The results obtained demonstrate that the model can accurately segment defects of various types and sizes, making it suitable for practical non-destructive testing applications.

The problem of wave reflection at the interface between a viscous fluid and a solid is considered under no-slip and slip boundary conditions. Within the framework of this problem, analytical expressions for the reflection coefficients and the components of the strain rate tensor are obtained. Under various contact conditions, dependences of the reflection coefficients and strain rate amplitudes on the wave incidence angles are constructed. These dependences are used to investigate the influence of the fluid viscosity, frequency of the incident wave, and slip parameter on processes of wave reflection and deformation at the solid-fluid boundary.

In the present work, the structural features and cellular interactions of powder materials and ceramics based on zirconium dioxide partially stabilized with yttrium oxide are investigated together with the special features of ceramic interaction with cell populations, which involves a comparative analysis of the cytotoxicity and the extent of red blood cell hemolysis. It is established that dioxide zirconium powders are in the two-phase state. High-temperature sintering allows dense ceramics to be obtained in a single-phase tetragonal state. It has been established that the average ceramic grain size after sintering is 0.475 μm. The ceramic materials based on partially stabilized zirconium dioxide have optimum biocompatibility parameters. The comparative analysis of biocompatibility of ZrO₂ (3%Y₂O₃), Ti, and TiNi samples has been carried out. The ceramic samples differ from Ti and TiNi samples by higher density of cellular populations on the flat surfaces of experimental samples, which is in agreement with the results of hemolysis and cytotoxicity investigations of the experimental samples.

The paper focuses on the ultrafine-grained (UFG) structure of ternary β‑alloy systems based on titanium, niobium, and zirconium, which changes the processes of heat generation and energy dissipation and storage during their deformation. It is shown that in the initial stage of deformation of the coarse-grained Ti-39.5 Nb-5 Zr-2 Ta-2 Sn (TNZTS) and Ti-39.5 Nb-5Zr (TNZ) alloys up to ε = 0.05 and 0.75, respectively, all plastic energy is absorbed by the alloys, which is associated with the dispersion hardening by the α‑ and ω‑phase nanoparticles in the TNZ alloy. The formation of the UFG TNZTS and TNZ alloys provides an increase in the initial strain stage up to ε = 0.065 and 0.115, respectively, owing to a substructural strengthening during severe plastic deformation. It is found out that in the initial stage, the UFG TNZ alloy dissipates the energy more effectively than does the TNZTS alloy due to the presence of β + α + ω structure, substructural strengthening, and dispersion hardening by the α‑ and ω‑phase nanoparticles.

The paper investigates the influence of nitriding in the plasma of a non-self-sustained arc discharge on the structure and properties of the R6М5 instrument steel. Nitriding is performed in five modes in order to obtain modified layers of various composition and properties. Microhardness measurements of the modified layers show that the most extended hardened layer is obtained after 500 °C nitriding. According to the metallographic and XRD analyses, the synthesized layers mostly consist of the nitrogen solid solution dissolved in the ferrite phase. This is explained by the high ion energy that provides sputtering of nitride layers and the formation of structural defects in the surface layers, accelerating the diffusion process in the steel.

The paper deals with the TiAlN-based coating synthesis using cathodic arc deposition. The deposition process is performed on an ion plasma vacuum installation consisting of the hot cathode and the additional plasma source “PINK”. The paper studies the influence of different values of the discharge current of the “PINK” on physical and mechanical properties of the coating and its structure and phase composition.

The paper presents the design and development of a low-temperature Stirling engine with the external heat supply, intended for autonomous cogeneration power systems. The engine utilizes thermal energy from a solar collector, which heats the working fluid to temperatures ranging from 90 to 100 °C. A key innovation of the proposed system lies in the significantly increased swept volume of the displacer, which exceeds the volume of the power piston by a factor of 20 to 40. This configuration enables a stable engine operation under relatively low temperature differentials between the heater and the cooler.

Experimental investigations, supported by numerical modeling, confirm the feasibility and efficiency of the proposed design. Under operating conditions with a temperature differential of approximately 65 to 75 °C and a working fluid pressure up to 0.3 MPa, the engine demonstrates a mechanical output ranging from 5 to 15 W and a corresponding thermal efficiency of 2 to 4%. Notable performance improvements are observed when air is replaced by helium with the incorporation of the working medium and a regenerator into the system.

The cogeneration capability of the system is realized through the recovery and utilization of residual heat from the cooling circuit for space heating and domestic hot water supply. The engine is designed for a fully autonomous operation in remote or off-grid areas, including rural settlements, greenhouse complexes, and other energy-demanding infrastructure. When integrated with a solar collector and thermal energy storage unit, the system offers the potential for continuous, around-the-clock electricity and heat generation.