Materials Science. Non-Equilibrium Phase Transformations.
Vol. 9 (2023), Issue 2

Table of Contents

  • Physical vapor deposited coatings with shape memory effect

    pg(s) 35-37

    Shape memory effects have been observed not only in bulk materials but also in PVD thin films. We have deposited copper-base shape memory alloys (SMAs) on Al substrates using DC sputtering. The coatings exhibit diffusionless transformation from the hightemperature austenite phase to the low-temperature martensite phase. This can be both, thermally controlled as a kind of two-way memory effect and stress-induced, giving a pseudoelastic behavior. The structures and microstructures of the coatings were analyzed by X-ray diffraction and optical microscopy. The martensitic transformation temperature was determined by dilatometric measurement. The coatings exhibit a martensite start temperature (Ms) very close to that of bulk materials. The SMA thin films have the ability to recover from large transformation stresses and strains when heated. In addition, their pseudoelasticity makes them potentially suitable as a protective layer against cavitation erosion.

  • The influence of the copper amount on structure and properties formation of aluminummatrix composite materials

    pg(s) 38-40

    The phase and structure formation of aluminum-matrix composite materials reinforced with titanium carbide during their synthesis and consolidation using the forging were investigated. The influence of copper additives on the structure formation, density, porosity, and hardness of aluminum-matrix composites was determined. The research results revealed the presence of Al+Cu+TiC phases in copperalloyed samples. Studies of density and porosity showed that the samples without copper additives were maximally densified after hot stamping and had minimal porosity, unlike the copper-alloyed composites.

  • Optical Logic Half Adder Based On Multi Ring Resonators Silicon Photonic Crystal Structures

    pg(s) 41-47

    In this paper, we introduce an innovative design for an all-optical half adder (HA) utilizing a pair of dual-ring resonators within a 2-dimensional square lattice photonic crystal (PC) framework, all achieved without the use of nonlinear materials. The all-optical HA encompasses both AND and XOR gates, each constructed with cross-shaped waveguides and twin ring resonators positioned in a 2D square lattice PC. These resonators are filled with silicon (Si) rods set in a silica (SiO2) medium. Employing the plane-wave expansion (PWE) and finite difference time domain (FDTD) techniques, we comprehensively analyzed and simulated the behavior of the AND and XOR gates. The simulation outcomes reveal that the internal light propagation within the device emulates the functions of traditional AND and XOR gates.
    Consequently, the proposed device displays promising potential for integration into optical arithmetic logic units, thereby enhancing digital
    computing circuits.
    The structural configuration encompasses an optical AND gate and an optical XOR gate, meticulously designed to operate within the Cband spectrum. The results unequivocally demonstrate a distinct demarcation between logic states 1 and 0, encapsulating a narrow power range that contributes to heightened robustness and minimized logic errors within the photonic decision circuit. Hence, the proposed HA stands as a pivotal building block in the creation of cutting-edge photonic arithmetic logic units.

  • The possibility of optimizing the properties of materials by using carbon nanostructures

    pg(s) 48-50

    Carbon nanomaterials occupy one of the leading places in many areas of technology aimed at creating new materials and solving a number of problems for various industrial needs, including materials needed for alternative energy. The development of humanity is accompanied by a constant increase in resource availability, which, despite the discovery of new deposits of fossil resources, can lead to a shortage of energy resources. Therefore, in the modern world, it is necessary to develop technologies that will promote the use and implementation of non-traditional alternative energy sources.

  • Al-Si-Ni composite with a low-temperature coefficient of linear expansion

    pg(s) 51-53

    The melt spinning and ball-milling techniques were applied to fabricate powder Al-Si-Ni alloy. The obtained Al-Si-Ni powder was compacted in pellet and solid-state sintered at 530 °C at a pressure of ~200 MPa. The phase composition, structure, coefficient of linear thermal expansion and hardness sintered samples were determined. The coefficient of linear thermal expansion of samples formed after sintering is in the range from 14.7×10-6 K-1 to 17.5×10-6 K-1. It is typical for steel. The synthesized powder composite, contains intermetallic Al3Ni phase, crystalline aluminum, and silicon. The hardness of sintering samples is 113 HV.

  • Long-time phase transitions in various vegetable oils

    pg(s) 54-55

    Vegetable oils are mixtures of mainly triglycerides of fatty acids. Their particles are large and have significantly different shapes. This causes problems in matching the molecules to each other and their translation and rotation necessary for the phase transition to occur. All this causes that phase transformations in vegetable oils have a long-time character. This article presents a comparison of the times of occurrence of this type of pressure-induced transformations for olive, sunflower, rapeseed and other oils. Possible causes of differences between them were also analyzed. The analysis of the phenomena occurring during phase transformations is crucial because during them the mechanical and electrical properties of oils change rapidly.

  • Mechanical and microstructure features of ti-al damping materials

    pg(s) 56-58

    Currently, metallic materials featuring a porous structure are extensively employed in passive safety mechanisms for absorbing mechanical energy during dynamic loads. Among these, aluminum foam-based damping materials are the most prevalent due to their adequate processability and cost-effectiveness. Nonetheless, expanding the array of properties within damping materials necessitates exploring the utilization of porous titanium-based products, known for possessing exceptional specific strength metrics. This avenue emerges as one of the most promising ways for advancing the domain of damping and energy-absorbing materials.

  • Effects of magnetohydrodynamic treatment and alloying on the structure and properties of Al-Si-Mg casting alloys

    pg(s) 59-61

    The possibility of improving the structure and properties of aluminum cast alloy based on Al-Si-Mg due to the melt treatment in the magnetohydrodynamic installation has been studied in this work. Also, the optimization of the chemical composition and select the optimal modes of heat treatment of the alloys to improve the structure and complex of properties was carried out. It was shown that the most effective alloying element which improve the strength characteristics of Al-Si-Mg alloy is lithium. It was found that the introduction of lithium into the alloy in the amount of 0.2% leads to the modification of the Al-Si eutectic and provides the increase in the yield strength and tensile strength by 15%, while the ductility increases more than three times as much as compared to that of the base alloy.

  • Study of fatigue failure for carburized carbon steel

    pg(s) 62-64

    This study presents the effect of carbonation on 1020 carbonate, low fatigue. The carbonation of the samples was carried out at a temperature of 900 ° C and at a variable time of 5-9 hours. After the process of carbonization, the process was carried out with a temperature of 500 ° C and 30 minutes. The hardness of the sample was tested before the Chemical heat treatment was 206.5 HB and the hardness of the carbonated samples at 900 ° C and at 5 hours was 209.3HB and the hardness of the carbonated samples at 900 ° C and for 6 hours was 209.5 HB. The carbonated sample salad was 900 ° C and 9 hours 211.4 HB. The boxes were heated at (850-900) ºC in an electric furnace for different durations or times. Fatigue was tested for samples before and after carbonation carburizing contributed to the improvement in fatigue strength in different proportions. The degree of improvement depended on the depth (thickness) of the hardened layer and on the microstructure of a carburized steel.