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For the first time, we performed functionalization of the surface of porous titanium nickelide alloys with bambusuril[6]-based macrocyclic compounds by different methods in order to provide the basis for saturation with therapeutic agents to impart antibacterial activity and accelerate its osteogenesis. It has been shown for the first time that the vacuum modification method is preferable for bambusuril deposition, since it provides a uniform deposition of organic matter on both the outer and inner surfaces of the pores. The effect of bambusuril deposition methods on the continuity, structure, and cytocompatibility of the porous titanium nickelide surface was evaluated. In vitro tests proved high biocompatibility and low toxicity of porous TiNi treated with BU[6] under vacuum. The SEM study of the structure of the surface layer of TiNi modified with BU[6] under the vacuum method showed that BU[6] agglomerates are uniformly deposited on the inner and outer surfaces of TiNi pores, which will provide an even saturation of BU[6] cavities with various pharmaceuticals, including antibiotics and inhibitors.

The phase composition, microstructure, and multiple shape memory effect of TiNi

The paper deals with the deformation curves and fatigue tests of the porous nickel–titanium (NiTi) alloy produced with self-propagating high-temperature synthesis. Deformation curves obtained for tension and three-point bending of porous NiTi plates demonstrate their viscoelastic deformation due to the austenite-to-martensite phase transformation. Scanning electron microscopy observations of the fractured surface show the regions of quasi-brittle fracture of martensite and ductile fracture of austenite. Brittle fracture is observed for nonmetallic inclusions and the porous structure coating of the intermetallic compound. Fatigue tests show that the brittle phases and inclusions have no critical negative effect on the strain and fatigue properties of the NiTi alloy. It is determined that 70% of the porous alloy specimens withstand 106 cyclic bending owing to the reversible austenite-martensite phase transformation in the parent phase which is one the components of the multi-phase porous alloy.

Martensitic transformations of the TN-10 titanium-nickelide alloys doped with V, Nb, and Ag at a level of 1 at % are studied. It is shown that the alloying elements (Ag, Nb, and V) cause an increase in the elastic stress inside the B2-phase structure and the consequent increase in the start temperature of the direct martensite transformation. Vanadium significantly affects such a temperature and provides an increase by about 45°C. Complicated martensite transformations (B2 → R → B19') take place in alloys with vanadium and silver, and simple transformations (B2 → B19') occur in alloys with niobium.

The work studies the influence of the silver dopant (

A gradient magnetron-sputtered three-layer laminated Ti–Ni–Ti coating is formed by the method of reaction synthesis on a titanium nickelide substrate. The resulting coating is designed for investigating the features of formation of the structure and phase composition in the coatings synthesized by self-propagating hightemperature synthesis in order to improve corrosion resistance of TiNi-implants. A comparative assessment of the as-formed and coated specimens demonstrates that nanocrystalline titanium oxycarbonitride layers present in the coating effectively improve its cytocompatibility.

The results of an investigation of surface wettability of TiNi-based alloys by water and DMEM-medium are presented. A comparative analysis of the wetting angle is performed after processing the specimens by grinding, sand blasting, oxidation in air, etching in a solution of acids, processing by vapor, hydrogen peroxide, and detergent solution in an ultrasonic bath. It is shown that oxidation in air and etching in acids increase the surface hydrophilic property of TiNi-based alloys. The highest hydrophilic value with the water wetting angle about 30° is achieved in the case of vapor treatment following sand blasting and treatment of the oxidized specimens with hydrogen peroxide. The differing influence of treatments on the wetting angle is attributed to variations in the surface energy of TiNi-based alloy specimens, which is affected by the microrelief and structural-chemical characteristics of the surface.

The objective of this study was to examine the mechanism how the surface of porous TiNi compounds produced by SHS method evolves. The prepared samples were investigated using light-microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive x-ray spectroscopy (EDS). The results indicated that the surface of all pores is represented by a granular stratum due to dendrite liquation by peritectic crystallization mechanism. The voids of 2–15 μm in size are formed owing to a capillary spreading of the liquid. Reaction gases with dissociated carbon, nitrogen, and oxygen are responsible for heat-and-mass transfer through the forming pores. High pressure-temperature effect of reaction gases on the melt causes the forming voids to coalesce, as well as transfers the peritectic liquid (PL) throughout the open pores catalyzing a distinctive spitted topography. It is through the chemisorption of gasiform nonmetallics by the pore surface melt, where these impurities are chemically bound, that it was formed a massive corrosion-resistant amorphous-nanocrystalline stratified shell deduced as an intermetallic oxycarbonitride layer.

Multi-structural polymer composites are widely used in the mechanical engineering, automotive, aviation and oil refining industries, as well as in the printing industry as a shock-absorbing deckle on the offset cylinders of printing machines. During offset printing, composites come into contact with inks and washing solutions, the components of which penetrate the material and cause the polymers to swell. This process degrades the print quality, and for this reason the study of its features is relevant. The prerequisites for this work are the study of the fundamental laws of diffusion and sorption of liquids by polymers with different micro- and macro-structures in different physical states and in different forms (e.g., films, sheets, fibers and fabrics). The combination of polymer materials in the composition of multi-structural fabric blankets makes it possible to obtain materials with unique mechanical properties and high resistance to liquid penetrating media and to use them in high-tech processes of multi-color printing with high resolution and color rendering. This article reports for the first time the kinetics and thermodynamics results obtained from the swelling of multi-structural polymeric blankets in solvents used in printing, and the effect of sorption of different polar liquids on the viscoelastic strain under compression during the operation of the damping systems of printing machines. Using mathematical models of activated liquid diffusion in polymers and deformation of a viscoelastic body, the swelling rate constants, solvent diffusion coefficients (the kinetic characteristics of the swelling process) and Flory–Huggins parameters (the thermodynamic characteristics of the interaction of the solvent with the composite) for composite–solvent systems with several chemical composition variants were determined. The elastic modulus and the viscosity coefficient of the composite under liquid saturation were calculated based on the experimental cyclic compression data. The range of change in the compression and restoration times of the polymeric blankets (0.09 s ÷ 0.78 s) was determined. It was shown that the composite swelled to a limited extent in all the studied liquids. All solvents used were thermodynamically poor (χ > 0.5). It has been established that rubber–fabric blankets coated with nitrile rubber are the least resistant to the action of dichloroethane, and that blankets with layers of polyolefins are not resistant to ethyl acetate. Water significantly affects the physicochemical properties of rubber–fabric blankets with a large proportion of cotton fabric layers. The data obtained can serve as a basis for optimizing the compositions of inks and cleaning solutions, as well as a theoretical basis for the thermodynamics of composite–solvent systems.

In this work, Ti-Ni-Ti nanolaminate was deposited on a TiNi substrate by magnetron sputtering. Subsequent synthesis in Ar at temperatures of 500, 700 and 900 °C was carried out. To investigate the effect of the reaction synthesis temperature for obtaining a dense thin intermetallic biofunctional coating, a comparative analysis of the morphology, structure, phase composition, mechanical properties and wettability of the coatings was carried out. It was found that crystallization processes have a different impact on the amorphous Ti and Ni layers depending on temperature. In all cases, multilayer gradient crystalline coatings were formed that bound to the substrate by the diffusion zone. The reaction synthesis temperatures of 500 and 700 °C are insufficient for reaction completion and complete transformation; therefore, the obtained thin loose layers are unstable under stresses caused by the substrate. Reaction synthesis in Ti – Ni – Ti nanolaminate at 900 °С formed a dense two-layer gradient coating 2 µm thick, which reliably protects the matrix from further diffusion of interstitial impurities and segregation of Ni atoms onto the surface. An analysis of the nano-indentation deformation diagrams showed that the coatings do not prevent the viscoelastic deformation of the TiNi substrate.

The mechanical behavior of samples of skin, tendon, muscle, and knitted mesh made from TiNi wire was investigated employing uniaxial cyclic tension and tension to rupture. The cyclic tensile stress-strain curves of all biological tissues exhibited the Mullins softening effect, characteristic of cyclic tension of hyperelastic materials. The mechanical behavior of knitted TiNi mesh made of 40-100 μm diameter wire is similar to soft biological tissues. All samples under uniaxial cyclic tension have exhibited the softening and delay effects, and in each of the diagrams, one can distinguish low and high-modulus regions. The deformation of the wire in the loading-unloading cycle is characterized by a superelastic behavior, which did not manifest itself in knitted TiNi mesh made from it. The knitted mesh from TiNi 60 μm wire at a minimum pre-tension has shown a minimal softening effect and a minimal decrease in stress hysteresis after the first cycle of physiological deformation of 6%. The discovered effects of hyperelastic behavior will make it possible to develop criteria for the selection and evaluation of knitted materials made of titanium nickelide for soft tissue reconstructive surgery. In vivo studies have shown good integration of the knitted TiNi mesh into living biological tissues under normal physiological stress.

Using the methods of SEM, EDS, and optical microscopy, a large number of non-metallic inclusions are revealed on the pore surface of a TiNi-based SHS-alloy. According to the XRD and EDS data, the surface is chemically and structurally inhomogeneous and its composition is close to that of a Ti4Ni2(O,N,C) intermetallic oxycarbonitride. An optical microscopy examination demonstrates that the entire surface is coated with a semi-transparent film. The results of XRD analysis allow assuming that in the formation of the surface of the TiNi-based porous material surface a significant role is played by the glassy phase and wollastonite, which imparts special physical-chemical properties and high biocompatibility to the alloy. SEM examination of morphological features of evolution of the mesenchymal cells on the pore surface of the TiNi-based SHS-material within the period 1–28 days shows that on the 7–14-th day the main elements of loose fibrous connective tissue are formed. Dense connective tissue is formed by the 21-st–28-th day.

We have studied the influence of silver addition in various concentrations on the structure and shape memory effect of biocompatible TiNiMoFe alloys. All these alloys at room temperature occur in a mixed state (B2 + R or B2 + R + B19′) with B2 austenite phase as the main component. It is established that small concentrations of silver (within 0.5 at % Ag) suppress the shape memory effect, while greater additions (1 at % Ag) stimulate the nucleation and growth of martensite crystals. This is accompanied by increasing content of the main B2 austenite phase and Ag particles in the alloy.

Samples of skin, tendons, muscles, and knitwear composed of NiTi wire are studied by uniaxial cyclic tension and stretching to rupture. The metal knitted mesh behaves similar to a superelastic material when stretched, similar to soft biological tissues. The superelasticity effect was found in NiTi wire, but not in the mesh composed of it. A softening effect similar to biological tissues is observed during the cyclic stretching of the mesh. The mechanical behavior of the NiTi mesh is similar to the biomechanical behavior of biological tissues. The discovered superelastic effects allow developing criteria for the selection and evaluation of mesh materials composed of titanium nickelide for soft tissue reconstructive surgery.

The effect of composition and thermal cycling on the phase transformations of multicomponent (TiNiMoFe)Ag alloys with a silver concentration of up to 1.5 at % is studied. Based on the temperature dependence of the electrical resistivity of the alloys under study, the characteristic temperatures are determined and a diagram of martensitic transformations is plotted. A correlation between the characteristic temperatures of the martensitic transformations and the structural-phase states of the (TiNiMoFe)Ag alloys is revealed.

The influence of annealing at 450°C for 1 h on the shape memory effect parameters of the Ti50Ni48.7V1Mo0.3 alloy is studied over a wide temperature range at a constant load. Annealing is shown to decrease the critical stresses of the martensitic shear, to increase the temperature hysteresis wide during a repeated shape memory effect, and to decrease this effect.

We have studied the influence of the surface layer on the parameters of the multiply repeated shape memory effect, developing stresses, characteristic temperatures, and intervals of martensitic transformations in thin (1 mm diameter) wires made of TiNi-based alloys. Examination of the surface layer structure showed that, in 1-mm-diameter TN-1V grade alloy wire, the oxide layer is about 15 μm thick and consists mostly of titanium, nickel, oxygen, and carbon. Removal of this surface layer leads to an increase in the maximum accumulated deformation, shift of the temperature interval of formation toward higher temperatures, and increase in the strength and plasticity characteristics.

A new type of biomedical shape memory alloys of the (Ti,Ni,Mo,Fe) Ag system was investigated by doping alloys with different concentration of Ag to 1.5 at.%. The role of an electronic factor of basic and alloying elements in the studied alloy was established. Martensitic transformations in TiNi-based alloys were studied for a series of initial and thermo-mechanically treated samples, i.e. after rolling, and the diagrams of the martensitic transformation of the (Ti,Ni,Mo,Fe)Ag system were constructed. It was revealed that rolling shifts the characteristic temperatures of martensitic transformations towards lower temperatures in comparison with the initial alloys which were not subjected to thermo-mechanical treatment.

Intermetallic porous SHS–TiNi alloys exhibit tangled and specific stress–strain characteristics. This article aims to evaluate the findings emanating from experiments using standard and proprietary instruments. Fatigue testing under repeated complex loading was used to measure the total number of load cycles before failure of the SHS–TiNi samples occurred. Of the tested samples, seventy percent passed through 106 cycles without failure due to the reversible martensite transformation in the TiNi phase, one of the prevailing constituents of a multiphase matrix. The fractured surfaces were analyzed using scanning electron microscopy and confocal laser scanning instruments. Microscopy studies showed that the entire surface of the sample is concealed by miscellaneous strata that result from the SHS processand effectively protect the porous alloy in a corrosive environment. Numerous non-metallic inclusions, which are also attributed to the SHS reaction, do not have a significant impact on the deformation behavior and fatigue performance. In this context, the successful in vivo functioning of porous grafts assessed in a canine rib-plasty model allows the bone substitute to be congruentially deformed in the body without rejection or degradation; it thus has a long operational life, often greater than 17 ×106 (22 × 60 × 24 × 540) cycles. It acknowledges the potential benefits of SHS–TiNi as a superior osteoplastic material and its high resistance to corrosion fatigue.

A gradient crystalline coating was created on a TiNi substrate by magnetron sputtering of a three-layer (Ti–Ni–Ti) nanolaminate with a layer thickness of 60–100 nm and subsequent argon annealing of the sample at 900°С. The coating was synthesized to study the features of its structure formation and phase composition, created by reaction synthesis to improve the corrosion resistance of TiNi implants. TEM, EDS, XRD, and EBSD methods showed that annealing initiated solid-state reaction processes between the nanolaminate layers and the substrate, as a result of which a three-layer amorphous nanolaminate transformed into a gradient two-layer coating bonded with the modified substrate through the diffusion zone. The diffusion growth of the nanolaminate layers during formation of the gradient coating was found to increase 10–20-fold. A comparative assessment of the substrate and coating has shown that oxide and oxycarbonitride layers in the coating effectively improve its biocompatibility.

The microstructural and functional behavior of TiNi-based wires with a silver content of 0–1.5 at.% was evaluated. The concentration range for Ag doping determined for the TiNi wires with potential for the medical industry was 0–0.2 at.%. Microstructure analysis of TiNi wires with different silver contents at room temperature indicated a multiphase structural state. Various internal structures with tangled grain boundaries were formed by intense plastic deformation. The nanocrystalline structure and phase state of wire with the minimum silver content (0.1 at.% Ag) provide full shape recovery, the greatest reversible strain, and optimal strength and ductility. TiNi ingots with a high Ag content (0.5–1.5 at.%) cracked under minimum load due to excess silver that crystallized along the grain boundaries and broke cohesion bonds between the TiNi grains.

The paper presents the results of study of the structure, phase composition and morphology of a nanocrystalline coating produced by reaction synthesis of a three-layer Ti–Ni–Ti nanolaminate. A characteristic feature of the coating is its full crystallinity, gradient structure and the absence of non-metallic inclusions. TEM and XRD analyses showed that reaction synthesis results in formation of a two-layer coating with a thickness of 0.9 – 1.0 μm. The thickness of the outer TiO + TiO2 and inner Ti4Ni2O layers is equal. There are no breaks between the synthesized coating and the substrate. The results of AFM and wetting showed that the surface of the synthesized coating is rougher than that of the deposited Ti–Ni–Ti nanolaminate. It exhibits an island relief and demonstrates hydrophilic properties.

Porous SHS-TiNi alloys, presented as a porous framework with a complex structure of the Core-Shell type, were studied by microscopic and structural methods. The core is the porous framework of an intermetallic TiNi phase. The shell was found to be a complex three-layer complex. An oxygen-hardened peritectic TiNi–Ti2Ni layer 1-6 μm thick forms an inner shell layer. Thermo and corrosion-resistant amorphous-nanocrystalline intermetallic oxycarbonitrides, saturated with O, N, C interstitial impurities, form middle and outer layers. The middle dense double layer 60-80 nm thick protects the TiNi matrix. The outer layer 1-15 μm thick has a loose layered structure, it is enriched in the MAX-phases Ti3SiC2, Ti3AlC2. The dense nano double layer provides a chemical passivity to the porous nickelide titanium alloy with shape memory, does not limit mobility and improves the ability to integrate into biological tissues.

The article presents a comprehensive study of the effect of different silver contents on the cells viability, structure and mechanical properties of TiNi-based alloy. Silver, crystallized in the form of pure particles, has a positive effect on cell viability. This is evidenced by a greater amount of cell mass on the surface of the alloy and an increase in the cell viability level by more than 30% at the presence of silver. A phase diagram of the Ag–Ni–Ti ternary system was constructed based on the structure of the two-component systems Ag–Ni, Ag–Ti and Ti–Ni and atoms from these systems. Due to the strong difference in the electronic structure and size factor of the components of the Ti–Ni–Ag ternary system, the limited solubility of Ag (~0.5 at% Ag) in the Ti–Ni binary compound was revealed. It has been established that the optimal combination of the physicomechanical properties of the alloys is achieved at silver concentrations, not exceeding 0.2 at% Ag.

The gradient coating synthesized on a nickelide titanium sample by sputtering a three-layer Ti-Ni-Ti laminate and annealing in air at 950–1000 °С was studied by XRD, SEM, TEM, and AFM methods. The thickness of the sputtered laminate layers was chosen equal to 0.5–1.0 μm to study the composition, structure and sequence of formation of the crystalline phases of the gradient coating. This thickness was sufficient for SEM and TEM studies and admissible large for XRD studies of phase composition. SEM and TEM techniques were used to determine the depth and patterns of grains occurrence of titanium carbonitrides. TEM and XRD techniques revealed that reactive synthesis of the coating is followed by transformation of the external amorphous layer of deposited titanium into heterogeneous crystalline titanium oxides. Crystallization of the oxide phase causes an increase in the volume of the external layer and intergranular cracking of the surface. AFM method showed an island microrelief of the external titanium layer formed during synthesis. The reaction synthesis of a multilayer laminate allows obtaining multifunctional nano-structured multilayer coatings with high chemical, mechanical and tribological characteristics, which ensures bioinertness of the surface of titanium nickelide implants.

The results of the study on properties of shape memory effect alloys, obtained on the basis of the experimentally determined temperature dependency of the shear martensitic stress in the alloyTi50Ni48.7Mo0.3V1, are described. It has been established that the total strain of the sample and the yield point reach a maximum value (ε = 25.5 %, σВ= 1280 МPа) at a test temperature of 300 K. It has been methodically shown how using this experiment in NiTi-based alloys it is possible to estimate temperature ranges of shape memory effect occurrence and to determine parameters of mechanical properties.

Porous TiNi alloys fabricated by self-propagating high-temperature synthesis (SHS) are biomaterials designed for medical application in substituting tissue lesions and they were clinically deployed more than 30 years ago. The SHS process, as a very fast and economically justified route of powder metallurgy, has distinctive features which impart special attributes to the resultant implant, facilitating its integration in terms of bio-mechanical/chemical compatibility. On the phenomenological level, the fact of high biocompatibility of porous SHS TiNi (PTN) material in vivo has been recognized and is not in dispute presently, but the rationale is somewhat disputable. The features of the SHS TiNi process led to a multifarious intermetallic Ti4Ni2(O,N,C)-based constituents in the amorphous-nanocrystalline superficial layer which entirely conceals the matrix and enhances the corrosion resistance of the unwrought alloy. In the current article, we briefly explore issues of the high biocompatibility level on which additional studies could be carried out, as well as recent progress and key fields of clinical application, yet allowing innovative solutions.