Materials Science. Non-Equilibrium Phase Transformations.
Vol. 11 (2025), Issue 1

Table of Contents

  • АI-орtimized angled multimode interference splitter with buried sin waveguide for highperformance O-band photonic networks

    pg(s) 3-7

    Traditional 1 × 2 multimode interference (MMI) splitters often encounter challenges such as high back reflections and limited output flexibility, which typically require additional structures like tapers or S-bends. These constraints limit their performance in advanced photonic networks. To overcome these issues, we propose an AI-optimized angled multimode interference (AMMI) splitter featuring a buried silicon nitride (SiN) core with silica cladding. By employing an angled propagation path, the device minimizes reflections to the source and allows greater adaptability for waveguide interconnections in dense photonic circuits. The design optimization was performed using a combination of artificial intelligence (AI) algorithms integrated with full-vectorial beam propagation method (FV-BPM) and finite-difference time-domain (FDTD) simulations. AI-driven parameter scanning enabled efficient exploration of the design space, improving device performance and robustness compared to manual optimization. The proposed AMMI splitter achieves an excess loss of 0.22 dB and an output imbalance of 0.001 dB at 1.31 μm, with total device length of 101 μm and thickness of 0.4 μm. Over the full O-band (1260–1360 nm), performance remains stable, with excess loss below 1.57 dB and imbalance below 0.05 dB, while maintaining back reflections as low as –40 dB. The compact CMOS-compatible design demonstrates high tolerance to fabrication deviations, making it highly suitable for large-scale integration. With its AI-enhanced optimization process, the proposed splitter supports high-speed, low-loss transmission for O-band photonic networks and data-center interconnects, offering scalability and reliability for next-generation optical systems.

  • Quantum Cone – Nano Source of Light with Dispersive Spectrum Distributed Along Height

    pg(s) 8-11

    A quantum cone is a structure consisting of a large number of quantum dots with a gradually decreasing diameter from the base to the top of the cone. This distribution of quantum dots leads to a dispersive radiated spectrum. The red edge of the spectrum is determined by the band gap of the bulk semiconductor, and the blue edge by the quantum confinement of excitons on top of the cones. We observe the kinetics of photoluminescence, obeying the stretched exponential law, from quantum cones formed on the surface of DLC. They are explained by an increase in the lifetime of excitons along the height of the cone from the top to the base of the cone and an increasing concentration of excitons at the base due to their drift in the quasi-built-in electric field of the quantum cone. Such time dependence of the photoluminescence spectrum gives the possibility of its discrimination spectrum on time. The possible visualization of the quantum cones of DLC using irradiation by a UV light source is shown. A quantum cone is a new type of nano light source, as it replaces two elements in a conventional spectrometer – a light source and a dispersive element: an ultra-fast monochromator. These features will make it possible to build a spectrometer to measure the absorption spectrum of individual nanoparticles or viruses.

  • Wave nature of the processes of high-speed mass transfer and local microalloying of laserhardened steels

    pg(s) 12-15

    The goal of this investigation was to research the nature of the formation of gradient and composite zones near non-metallic inclusions during laser treatment of the steels. The materials for investigation were commercial steels containing different non-metallic inclusions. The specimens of different steels were exposed to laser beaming on the installations GOS-30M. The research methods were applied: petrography, X-ray microscopy (MS-46 Cameca, “Nanolab – 7”) and optical microscopy (Neophot-31) to study steel matrix near non-metallic inclusions and to identify of the inclusions. Nanohardness of the steel matrix near inclusions (“Nano Indenter II”) was analyzed. Peculiarities of saturation of the steel matrix by elements of non-metallic inclusions during different regimes of laser action were investigated. It was shown the role of that process in the formation of local structure of steel matrix near non-metallic inclusions. The features of the formation of gradient and micro composite saturation zones of a steel matrix under conditions of abnormal mass transfer from nonmetallic inclusions during laser processing are discussed. The difference in the rates of abnormal mass transfer of chemical elements of non-metallic inclusions into a steel matrix at the moment of laser melting is shown.

  • Radiation shields and their potential applications in space

    pg(s) 16-17

    There is a mixture of different types of radiation in space. It includes both electrically charged particle radiation, electrically neutral particle radiation, and electromagnetic radiation. For this reason, building radiation shields for space equipment or vehicles is a challenge. This work presents old and new solutions for radiation shields that have potential for use in space, along with their advantages and disadvantages.

  • Features of structure formation and properties of cast titanium bronzes obtained using thermally synthesized powder ligatures

    pg(s) 18-20

    The study of the effect of heat treatment regimes on the structure and physical and mechanical properties of smelted titanium bronzes showed that after quenching castings from 800 °C, their structure of cast alloys has a significantly dendritic character and significantly lower hardness compared to the as-cast state. A significant increase in the level of hardness and strength of the alloys is achieved by aging at a temperature of 400 °C. The highest level of hardness and strength is characterized by the Cu – 2,7 % Ti alloy without aluminum. The dependence of the electrical conductivity of bronze additionally alloyed with 0,5 % Al and 3,0 % (wt.) Ni on the titanium content is extreme: the maximum conductivity (~33 % IACS) is observed for the alloy with 1,5 % (wt.) Ti. The alloying of titanium bronze (3 % Ti, 0,7 % Ni, 0,03 % B) and heat treatment of quenching at 900 °C, aging at 450 °C with isothermal holding for 0,5 h, contributed to an increase in the complex of physical and mechanical properties (tensile strength 870 MPa, yield strength 830 MPa, and hardness 106 HRB).

  • Physical properties study of ferromagnetic Permalloy thin films

    pg(s) 21-24

    We fabricated Permalloy thin films of different thicknesses, using thermal evaporation under vacuum, onto Si (100) substrates. We examined the influence of Py thickness on their physical properties. The surface morphology, structure, microstructure, chemical compositions and electrical properties, are performed by atomic force microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy equipped with an energy dispersive X-ray analyzer (SEM-EDS), and the Hall Effect measurement system (HMS-5300). The analyses of X-ray diffraction spectra confirmed the formation of the Ni3Fe phase and inferred that all the films crystallize in a CFC structure with a preferential <111> orientation. The crystallites size and the lattice parameter, computed from the dominant (111) X-ray diffraction peak, decreased with increasing Py/Si film thickness. Also, the lattice parameter values, obtained for all samples, were fairly close to the bulk value. SEM micrographs of the samples clearly exhibited a non-uniform distribution of quasi-spherical aggregates on the granular surface of the Py/Si films, as well as the presence of micro-cracks for the thickest film. Furthermore, AFM images indicated the formation of crystallites according to Stranski-Krastanov mode for the Py/Si films, with roughness values ranging from 0.2 to 2.5 nm. Electrical measurements revealed that the electrical resistivity decreased with increasing film thickness whereas the mobility increased. The spontaneous magnetization increases with thickness from 600 to 760 emu/cm3, and the coercivity decreases following a t-n Néel law.

  • Regeneration of filter elements for cleaning hydrocarbon compounds from powdered polyethylene particles

    pg(s) 25-26

    The article presents information on the regeneration of filter elements (filter components) made of tin-phosphorus bronze powders that were tested during polyethylene production in the unloading unit of the ethylene polymerization reactor for cleaning hydrocarbon compounds from polyethylene powder particles. It was found that during the testing period, the filter elements met the requirements specified in the equipment regulatory documents. After completing the tests, two thermal regeneration cycles were carried out: at LLC “Stavrolen” and at O.V. Roman Powder Metallurgy Institute. It was found that in the first case, the filter element throughput was restored to 67.5% of the initial value, and in the second case, to 97.2%, which indicates the multiple regeneration possibility of spent powder filter elements when used to clean hydrocarbon compounds from polyethylene powder particles.

  • The Interplay of Laser Metal Processing and Non-Equilibrium Phase Transformations

    pg(s) 27-29

    This comprehensive report explores the intricate relationship between modern laser metal processing techniques and the nonequilibrium phase transformations they induce in a wide range of materials. The central thesis is that methods such as laser cutting, welding, and additive manufacturing are not merely thermal processes, but rather precise engineering tools that fundamentally alter a material’s state by subjecting it to extreme conditions.

  • Effect of chromium on the microstructure of AlSi7Mg alloy with increased iron content

    pg(s) 30-33

    The need to protect the environment by reducing the energy intensity of production, the amount of waste, and reducing greenhouse gas emissions, as well as shrinking bauxite resources, means that secondary raw materials are playing an increasingly important role in aluminum alloy smelting. However, the increase in the proportion of scrap results in a higher content of various impurities, the worst of which is iron in the group of metallic ones. It is well known that manganese is one of the most commonly used additives to neutralize morphologically unfavorable β-Al5FeSi phases. However, there is little information about the effects of other transition elements, such as chromium. Accordingly, the study’s results concern the effect of chromium on the microstructure of AlSi7Mg alloy with increased iron content (from 0.4wt.% to 1.4wt.%, in 0.2% increments). Based on SEM/EDX and XRD studies, it was found that the addition of chromium causes the transformation of the lamellar-needle phase β-Al5FeSi into the α-Al13(Fe,Cr)4Si4 phase with a dendritic morphology (so-called “Chinese script”). However, care should be taken not to exceed the permissible value of the chromium/iron quotient (Cr/Fe ~ about 1/3). Otherwise, the morphology of the α-Al13(Fe,Cr)4Si4 phase changes from more “fluffy” to massive polygons. This is accompanied by an unfavorable increase in the slime ratio from about 1.6 to more than 3.0%.