Purpose. The study aims to develop and characterize a new nanostructured FeCo0,854Nb0,146NiB0,7Si0,3 high-entropy metallic glass with enhanced soft magnetic and mechanical properties. The research seeks to explore the interplay between the alloy’s amorphous structure and its functional properties to advance the understanding of high-entropy metallic glasses. Design / Method / Approach. The amorphous films of the FeCo0,854Nb0,146NiB0,7Si0,3 alloy was synthesized using splat-quenching technique. The cooling rate, estimated based on the film thickness, was ~106 K/s. Structural properties were analyzed via X-ray diffraction (XRD), differential thermal analysis (DTA), and electrical resistivity measurements. Magnetic properties were assessed using a B–H curve tracer and vibrating sample magnetometer, while microhardness was measured with a PMT-3 tester. Findings. The alloy exhibits a fully glassy structure with a crystallite size of ~3 nm, low coercivity (40 A/m), high saturation magnetization (74 A·m2/kg), and microhardness ≥ 8000 MPa, indicating decent soft magnetic and mechanical properties. Theoretical Implications. The research provides significant insights into the role of atomic-size differences, configurational entropy, and thermodynamic parameters in stabilizing the glassy phase in high-entropy alloys. It advances the theoretical framework for designing high-entropy amorphous materials. Practical Implications. The characteristics of the material make it promising for use in electronic devices and mechanical engineering parts. Originality / Value. This study provides a comprehensive analysis of the high-entropy metallic glass FeCo0,854Nb0,146NiB0,7Si0,3, offering new insights of its magnetic and mechanical properties through advanced characterization techniques. Research Limitations / Future Research. Further studies are needed to investigate the long-term stability of the fabricated amorphous alloy. Article Type. Applied Research. PURL: https://purl.org/cims/4.284

Purpose. The study is aimed at finding a constructive balance between the mass and cost of composite panels with stiffeners that are subjected to combined loading. The optimization was carried out taking into account real operation conditions, when a slight improvement in one of the parameters can significantly affect the efficiency of the structure. Design / Method / Approach. The work integrates engineering mechanics and mathematical modeling with the construction of a vector optimization model, for the solution of which the procedure of forming an integral quality criterion was applied, which considers expert assessment and the principle of guaranteed results. Conclusions. The proposed methodology allows not only to determine the optimal structural parameters for panels with different reinforcement options but also provides flexibility for adaptation to variable loads and constraints. The model was successfully tested on the example of six load scenarios for panels with rectangular and angular ribs. Theoretical implications. The development contributes to the development of multi-criteria optimization of composite structures, in particular by refining models and expanding the principles of evaluating the trade-off between criteria. This lays the foundation for further research in the field of aircraft design, where criteria may contradict each other. Practical implications. The results formed the basis for the creation of a software package that allows for the determination of the most appropriate options for structural reinforcement depending on the constraints and requirements. Originality / Value. The human-machine decision-making system underlying the approach allows for expert intuition to be considered without losing the accuracy of mathematical modeling. This is extremely valuable for industries where every gram of weight and every hryvnia of costs are critical. Research limitations / Further research. The main limitation is the focus on only two criteria – mass and cost. Further exploration should be directed towards expanding the number of indicators. Article Type. Applied Research. PURL: https://purl.org/cims/4.278

Purpose. This study aims to improve the accuracy of methods for determining fin efficiency. Its goal is to derive calculation relationships for finning coefficients that account for transverse temperature non-uniformity within the fin cross-section. Design / Method / Approach. The article presents the reduction of the heat conduction equation for a fin to a dimensionless form, based on dimensional analysis of the variables involved. Further development relies on analyzing the results of numerical simulations and their subsequent generalization. To this end, the gradient descent method is applied, minimizing the quadratic error function. Findings. A criterial dependence has been formulated to complement the derived heat conduction equation. Test calculations and comparisons with numerical simulations in Ansys Fluent confirm an improvement in calculation accuracy when using the proposed equation. Theoretical Implications. This paper addresses factors previously neglected in the analysis of heat transfer in fins. The results of the study thus complement existing approaches to determining finning coefficients. Practical Implications. The derived criterial relationship will enhance the accuracy of heat transfer calculations in the chambers and gas generators of liquid rocket engines. Originality / Value. The paper introduces an original criterial relationship that accounts for temperature non-uniformity across the fin cross-section. Incorporating this factor improves calculation accuracy, highlighting the practical value of the developed equation. Research Limitations / Future Research. This study focuses on rectangular fins; therefore, the proposed model is not applicable to fins with variable thickness in the ducts of liquid propellant rocket engines (LPREs). Developing a fin model without these limitations will be the objective of future research on this topic. Article Type. Applied Research. PURL: https://purl.org/cims/4.299

Purpose. To optimize criteria for evaluating the implementation of wear-resistant materials to reduce production costs and equipment downtime. Design / Method / Approach. The study employed an analytical review of publications, spectral and metallographic analysis of alloys, a gravimetric method for assessing wear resistance, and heat treatment to enhance it. Findings. An analysis of challenges in developing materials for mining, metallurgical, and construction equipment was conducted. It was established that component service life must align with equipment maintenance schedules. New materials with enhanced wear resistance may be economically unviable due to high costs or inability to realize durability benefits. A balance between cost and service life is achieved by analyzing operating conditions and defining material and technology requirements. Theoretical Implications. The study expands knowledge on reducing production costs by identifying criteria for the effective implementation of materials and technologies. Practical Implications. A multi-criteria analysis is proposed for adopting new materials and technologies in the production of components for mining, metallurgical, and construction equipment, reducing costs and downtime. Originality / Value. The methodology uniquely optimizes material selection by aligning component durability with maintenance schedules, minimizing downtime. Its innovative alloy development resolves conflicting material requirements, enhancing production efficiency. Research Limitations / Future Research. Limitations include a focus on specific materials; future research should explore a broader range of materials and conditions. Article Type. Empirical. PURL: https://purl.org/cims/4.287