Layered amorphous-crystalline TiNiCu alloy ribbons produced by ultrarapid quenching from the liquid state (melt spinning technique) show the two-way shape memory effect without additional processing, which makes them applicable to various micromechanical devices (microtweezers) for gripping and manipulating microobjects. The present work is devoted to the study of the influence of the rejuvenation process (cryogenic thermal cycling) and the thickness of the crystalline layer on the structure and functional properties of quasi-binary TiNi-TiCu alloy with the copper content 25 at

The fracture strength was compared in a scratch test of coatings based on the ZrN system with the introduction of Ti, Nb and Hf, which were deposited on a titanium alloy substrate. The coatings were deposited using Controlled Accelerated Arc (CAA-PVD) technology. In coatings that simultaneously include Zr and Ti, a nanolayer structure is formed, while in coatings without Ti, the formation of a monolithic single-layer structure is observed. The comparison was carried out according to two parameters: adhesion strength to the substrate and overall coating strength. The (Zr,Hf)N coating showed better resistance to destruction, but had worse adhesion to the substrate. As a result, although the coating is retained directly in the scribing groove, a large area of delamination and destruction is formed around the groove. The (Ti,Zr,Nb)N coating, with its somewhat lower strength, has a high adhesion to the substrate; no noticeable delamination is observed along the groove boundary. In this paper, not only is the fracture resistance of various coatings deposited on a titanium alloy substrate compared, but the nature of this fracture is also investigated depending on the composition of the coatings.

The (Ti,Y,Al)N coating was deposited at different values of the yttrium cathode arc current (65, 85, 105, and 125 A). With an increase in the arc current from 65 to 105 A, an increase in the Y content in the coating from 30 to 63 at% is observed; however, with a further increase in the arc current to 125 A, the yttrium content practically does not change. This effect can be associated with an increase in the proportion of microparticles in the plasma flow at high values of the arc current. These microparticles do not reach the surface of the substrate, falling on the walls of the chamber. With an increase in the arc current, the dominant shape of the microparticles changes. If at 65 A relatively small (up to 3 mu m) microparticles of a regular spherical shape dominate, then at 85 A a noticeable amount of irregularly shaped microparticles with sizes of 3-5 mu m is observed, and with a further increase in the arc current, large microparticles up to 30 mu m in size are formed. The value of the modulation period of the studied coatings is 42-67 nm. The change in the modulation period lambda depending on the arc current of the yttrium cathode has a character close to linear, increasing with increasing arc current. From the point of view of hardness, scratch test and wear resistance during turning, only coatings deposited at arc currents of 65 and 85 A have prospects for effective operation as a wear-resistant coating.

Layered amorphous-crystalline ribbons of rapidly quenched TiNiCu alloy with two-way shape memory effect (TWSME) have proven to be a promising material for microtweezers used for the gripping and manipulation of micro- and nanoscale objects. Ribbons with different crystalline layer thicknesses have been produced in this work by melt spinning at variable melt cooling rate. A method has been proposed and an innovative experimental setup has been designed for TWSME studies. We show that reducing the melt cooling rate one can increase the thickness of the crystalline layer, accompanied by an increase in the minimum ribbon bending radius and the maximum reversible deformation during the implementation of the TWSME. The test ribbon samples have been rejuvenation treated (cryogenic thermocycling). It has been shown that cryothermal treatment can tangibly increase the TWSME reversible deformation and significantly reduce the width of the shape change temperature hysteresis. The latter effect can be used for improving the performance of microdevices, in particular microtweezers, based on rapidly quenched amorphous-crystalline ribbons.

The studies are focused on the properties of the multilayer composite coating based on the (Ti,Y,Al)N system with high content of yttrium (about 40 at.%) of yttrium (Y). The hardness and elastic modulus were defined, and the resistance to fracture was studied during the scratch testing. Two cubic solid solutions (fcc phases), including c-(Ti,Y,Al)N and c-(Y,Ti,Al)N, are formed in the coating. The investigation of the wear resistance of the (Ti,Y,Al)N-coated tools during the turning of steel in comparison with the wear resistance of the tools with the based on the (Ti,Cr,Al)N system coating and the uncoated tools found a noticeable increase (by 250%–270%) in rake wear resistance. Active oxidation processes are observed in the (Ti,Y,Al)N coating during wear. It can be assumed that yttrium oxide is predominantly formed with a possible insignificant formation of titanium and aluminum oxides. At the same time, complete oxidation of c-(Y,Ti,Al)N nanolayers is not observed. Some hypotheses explaining the rather high performance of a coating with a high yttrium content are considered.

В работе рассмотрены достижения последних лет в области проектирования и изготовления искусственных самовосстанавливающихся материалов и композиционных систем, которые могут быть использованы в качестве защиты от повреждающих факторов внешней среды. Рассмотрены принципы самозалечивания в искусственных материалах и прототипы таких материалов, имеющих потенциал применения в космической технике. Особое внимание уделено полимерным материалам с динамически подвижными молекулярными связями и композитным материалам с внутренними наполнителями, осуществляющими процессы самозалечивания. Отмечено, что слоистая структура композитного материала с внутренним вязкотекучим наполнителем, за счёт направленного массопереноса вязкотекучего компонента и его консолидации в области дефекта, способна быстро восстанавливать герметичность материала после сквозных повреждений. Продемонстрированы лабораторные прототипы самозалечивающихся материалов, среди которых выделяются слоистые композитные материалы, способные самостоятельно восстанавливать герметичность менее чем за секунду, что открывает перспективы их использования в надувных конструкциях для защиты от утечек внутренней атмосферы. The paper considers the achievements of recent years in the design and manufacture of artificial self-healing materials and composite systems that can be used as protection against damaging environmental factors. The principles of self-healing in artificial materials and prototypes of such materials that have the potential to be used in space technology are considered. Particular attention is paid to polymeric materials with dynamically mobile molecular bonds and composite materials with internal fillers that carry out self-healing processes. It is noted that the layered structure of a composite material with an internal viscous filler, due to the directed mass transfer of the viscous component and its consolidation in the defect area, is able to quickly restore the tightness of the material after through damage. Laboratory prototypes of self-healing materials have been demonstrated, among which layered composite materials stand out that can independently restore tightness in less than a second, which opens up prospects for their use in inflatable structures to protect against leakage of the internal atmosphere.

Insect pest control requires fundamental knowledge of their physiology and behavioral responses. However, due to the small size of insects in general and their sensory organs (sensilla), in particular, the study of the physiology of insect sensory systems has until recently been limited by insufficient accuracy and selectivity of experimental mechanical action. To eliminate this gap in the study of insects nervous system, a microrobotic technology is proposed based on a micromechanical device - microtweezers based on a layered structural composite of $\text{Ti}_{50} \text{Ni}_{25} \text{Cu}_{25}$ alloy with a shape memory effect (SME), combined with a temperature control system and a three-coordinate piezoelectric micropositioner. Microtweezers with SME selectively capture the smallest sensilla of the studied insects, enabling their precise mechanical stimulation with simultaneous recording of physiological responses generated by sensilla by methods of electric impulse derivation in the nerve centers of the insect.

The local crystalline environment of Ni and Cu atoms in the quasi-binary TiNi-TiCu shape memory alloys containing 30 and 40 at.% Cu has been studied using EXAFS spectroscopy. Amorphous melt-spun alloy ribbons have been crystallized by isothermal annealing or by exposing to a short (10 ms) electric pulse. Analysis of the EXAFS spectra has shown that electropulse crystallization has a more noticeable effect on the local atomic structure of austenite compared to martensite. In particular, it leads to a decrease in the local disorder of atoms in the Cu coordination shells, a decrease in the lengths of Cu-Ni and Cu-Cu bonds, hinders an increase in the lattice parameter of the austenite phase and stabilizes its crystal structure. The observed changes in the local atomic structure of the austenite phase of the alloys contribute to the improvement in the shape memory properties.

The article considers the processes of cracking and oxidation in the nanolayer coatings of (Cr,Y,Al)N and (Mo,Y, Al)N with a high (about 50 at%) content of yttrium (Y). The studies were carried out during the turning of steel with subsequent investigation of the wear area using scanning (SEM) and transmission (TEM) microscopes. Although the main parameters (elemental composition and structure) are identical and the values of hardness and elastic modulus are close, tools with the coatings under consideration demonstrated noticeable difference in wear resistance. The (Mo,Y,Al)N coated tool had a wear resistance 45% higher than the (Cr,Y,Al)N coated tool and 30% higher than the (Ti,Cr,Al)N reference coated tool. Active formation of cracks is detected in the (Cr,Y,Al) N coating, while oxidation wear dominated in the (Mo,Y,Al)N coating. Therefore, coatings containing layers of materials characterized by an increased tendency to oxidize, but at the same time providing a favorable compositional effect, can be effectively used. This is possible provided that the oxidation-resistant layers protect the oxidation-prone layers from active contact with oxygen.

Alloys of the quasibinary TiNi-TiCu system manufactured by melt quenching in the form of thin 20–50 μm ribbons have proven to show good potential as materials for the fabrication of micromechanical devices. At high cooling rates (about 106 K/s), this method allows producing high-copper (more than 20 at.%) amorphous alloys which exhibit an excellent shape-memory effect after crystallization. Their properties are known to largely depend on the crystallization conditions and the structure of the initial amorphous material acting as a precursor for the formation of crystal phases. It has been shown recently that the rejuvenation procedure (cryogenic thermocycling) of metallic glasses is one of the most promising methods of improving their properties. In this study, we investigated for the first time the effect of cryogenic thermocycling of rapidly quenched amorphous TiNiCu on the initial state, as well as on structure formation and the phase transformation patterns of subsequent crystallization conducted using various methods. The effect was analyzed utilizing the methods of scanning and transmission electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry. The results show that rejuvenation treatment slightly reduces the glass transition and crystallization onset temperatures and moderately changes the sizes of structural features (grains, martensite plates), the quantity of the martensite phase, and the characteristic temperatures and enthalpy of the martensitic transformation.

Insect pest control requires fundamental knowledge of their physiology and behavioral responses. However, due to the small size of insects, in general, and their sensory formations (sensilla), in particular, the study of the physiology of insect sensory systems has until recently been limited by insufficient accuracy and selectivity of experimental mechanical action. To eliminate this gap in the study of insects, a physical technology is proposed based on a micromechanical device - microtweezers based on a layered structural composite of Ti50Ni25Cu25 alloy with a shape memory effect (SME), combined with a temperature control system and a three-coordinate piezoelectric micropositioner. Microtweezers with SME selectively capture the smallest sensilla of the studied insects, enabling their precise mechanical stimulation with simultaneous recording of physiological responses generated by sensilla using methods of impulse derivation in the nerve centers of the insect.

Ti-TiN-(Y,Ti,Al)N coatings with a three-layer architecture (adhesive Ti layer, transition TiN layer, and wear-resistant (Y,Ti,Al)N layer) were studied. When depositing coatings, three arc current values of the yttrium cathode were used: 65, 85, and 105 A. The yttrium contents in the coatings were 30, 47, and 63 at. %, respectively. When turning 1045 steel, a coating with 30 at. % yttrium showed better wear resistance compared to a commercial (Ti,Cr,Al)N coating. The coating with 63 at. % yttrium did not show an increase in wear resistance compared to the uncoated sample. Nanolayers with a high yttrium content are oxidized more actively compared to nanolayers with a high titanium content. Phase analysis shows partial retention of the initial phases (Y,Ti,Al)N and (Ti,Y,Al)N during the formation of the Y2O3 oxide phase in the outer layers of the coating and the presence of only the initial phases in the deep layers. Coating nanolayers with high contents of aluminum and yttrium lose their original structure to a greater extent during oxidation compared to layers without aluminum.

The paper describes the results of the study of Ti-TiN-(Ti,Al,Cr)N nanostructured coatings with varying modulation period λ. The study was focused on the coatings with the modulation period λ, increasing from 20 to 300 nm and decreasing from 300 to 20 nm. A sample with the constant modulation period λ = 50 nm was assumed as an object of comparison. The hardness of the coatings and their resistance to fracture during scratch testing were found. The structure of the coatings was studied using scanning (SEM) and transmission (TEM) electron microscopy. The data on the elemental and phase composition of the coatings were compared. It has been found that a coating with an increasing modulation period λ provides higher tool wear resistance during the turning of steel. The studies reveal differences in the patterns of cracking in the coatings under consideration. The crystalline structure of the coatings was studied. It has been found that, with identical grain sizes, the coatings have noticeable differences in terms of texture severity.

The study of the effect of electropulse treatment with a variable duration on the crystallization processes and the structure of a amorphous TiNiCu alloy with 25 at.% Cu in comparison with isothermal annealing and heating at a constant speed was carried out. The alloy was fabricated by rapid-quenching from the liquid state (melt spinning technique) at the cooling rate of the melt of about 10 6 °C/s in the form of a ribbon with a thickness of 28 μm with a surface crystal layer with a thickness of about 2-3 μm. To remove the crystal layer, the method of double-sided electrochemical polishing was used. The studies were carried out by methods of differential scanning calorimetry, metallography and scanning electron microscopy. It was established that the formation of the crystalline phase in the electropulse treatment of the amorphous ribbon occurs from the surface to the inner part due to the predominant formation and growth of columnar crystals with subsequent nucleation and growth of crystals in the rest of the ribbon.

The paper considers the influence of the spatial arrangement of samples in the unit chamber on parameters of deposited coatings when using a vacuum arc evaporator with controlled accelerated motion of a cathode spot of Arc-PVD (CAA-PVD) compared to a standard used in NNW6.6 evaporator with magnetic cathode spot retention by axial field. The distance from a sample to the cathode surface and an offset of the sample about the central axis of the cathode were varied. The study reveals the regular patterns' influence on the spatial sample arrangement on coating properties, such as thickness, microhardness, surface macroparticle content density, and crystal structure. Using the CAA-PVD technology allows reducing the distance from the cathode surface to the samples from 230 to 150 mm, forming a coating with a higher microhardness and lower density of microparticles than the standard used in NNW6.6 evaporator. It is found that a CAA-PVD evaporator forms a coating with a higher hardness and lower density of microparticles compared to a NNW6.6 evaporator. The application of the CAAPVD technology significantly (by 30-270%) reduces the density of microparticles on the coating surface, and the coating is characterized by a more uniform thickness and distribution of microparticle density.

Rapidly quenched thin ribbons of quasi-binary TiNi–TiCu system alloys with high copper contents (more than 20 at.%) are promising materials for the manufacture microactuators due to excellent shape memory effect with narrow temperature hysteresis. Amorphous TiNiCu alloys with a copper content of 30–40 at.% were obtained by the melt spinning technique at a melt cooling rate of 106 K/s in the form of ribbons with a thickness of about $40\ \mu\mathrm{m}$. The crystallization of the alloys was carried out using electropulse treatment with duration in the range from 5 to 1000 ms. X-ray diffraction studies showed that at room temperature all alloys exhibit B19 martensitic structure. Microstructure of the ribbons consists of columnar crystals near the ribbon surfaces and large grains with characteristic sizes from 3 to $12\ \mu\mathrm{m}$. TEM examination revealed a subgrain structure with nanoscale martensite plates (20-80 nm). The alloys exhibit one-stage martensitic transformation $\mathrm{B}2\leftrightarrow \mathrm{B}19$ and pronounced shape memory effect in the temperature range of 55-75°C.

A procedure for the synthesis of borosiloxane compounds by the reaction of polydimethylsiloxane with boric acid upon heating in a cylindrical reaction vessel is presented. The mixing of the reaction components in the considered method occurs spontaneously due to the sublimation of boric acid vapor and its movement in a natural way from the lower part of the reaction vessel to the upper part through the volume of polydimethylsiloxane. The technique makes it possible to synthesize borosiloxane compounds without the use of special equipment, increased energy consumption, and chemical solvents.

The article discusses the specifics of the formation of the coating structure when the vacuum arc evaporator with controlled accelerated motion of a cathode spot of Arc-PVD (CAA-PVD) is used. The article also presents the results of the studies focused on the relationship between the shape and the crystalline structure of the microparticles formed during the coating deposition process and the spatial arrangement of a sample in the chamber of the unit. The influence of the structure of the contact zone between a microparticle and the substrate surface on the crystalline structure of a microparticle was analyzed. The conducted experiments detected the relationship between a solidified microparticle and its initial size. The studies focused on the phase composition of microparticles confirmed a hypothesis on the formation of a nitride shell around a metallic core.

The article deals with the properties of the Ti-TiN-(Ti,Cr,Al)N multilayer composite coatings with a nanolayer structure of their wear-resistant layers and the nanolayer period λ within a range from 10 to 900 nm. The studies were focused on the coating nanostructures and the influence of the nanolayer period λ on the performance properties of coated cutting tools during the turning of American Iron and Steel Institute (AISI) 420 (230 HB) martensitic stainless steel. The investigation found that the coatings with the nanolayer period λ = 10–25 nm demonstrated the best resistance to the crater formation on the rake face of cutting tools and to flank wear. The highest wear resistance was demonstrated by a coated tool with the nanolayer period λ = 10 nm.