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The influence of the pulse frequency and duty cycle on the elemental composition, microstructure, and mechanical properties of Ti–Al–Ta–N coatings deposited by middle-frequency magnetron sputtering is studied. An increase in the pulse frequency and duty cycle is found to lead to a decrease in the deposition rate and sputtering yield as well as to variations of the coating composition. The coatings deposited at a pulse frequency of 50 kHz have a denser mixed microstructure, while those obtained at 100 kHz are characterized by pronounced columnar morphology. The hardness of the coatings slightly decreases with increasing duty cycle. Thus, the coatings with dense microstructure and maximum hardness are obtained at a pulse frequency of 50 kHz and a duty cycle of 60%.

The composition, structure and mechanical properties of Ti–Al–Ta–N coatings obtained by high-power impulse magnetron sputtering and direct current magnetron sputtering have been studied using energy-dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, and nanoindentation. It has been established that for high-power impulse sputtering, the current and power of the magnetron discharge increase exponentially during the pulse and reach peak values that are an order of magnitude higher than similar characteristics for magnetron sputtering at direct current. A high level of ionization of the sputtered particles caused a significant increase in the number of ions in the particle flux deposited on the substrate. The suppression of the growth of columnar grains and the formation of a denser and more homogeneous microstructure were ensured by an increase in the intensity of ion bombardment of the growing coating. This made it possible to improve its mechanical characteristics.

Effect of Si content on the patterns of deformation and fracture of Ti 1– x – y – z Al x Ta y Si z N coatings under uniaxial tension is investigated. The nanoindentation method has shown that the coating with z  = 0.10 has the maximum hardness, which is caused by the formation of a thin grain-boundary amorphous SiN x phase. At the same time, the Ti 0.35 Al 0.40 Ta 0.10 Si 0.15 N coating showed the highest fracture resistance and adhesive strength. It is found that this effect is due to the suppression of the growth of columnar grains in this coating and the formation of a two-phase amorphous-nanocrystalline structure, which makes it difficult for cracks to propagate.

The structure and mechanical properties of magnetron-sputtered Ti–Al–Ta–N and Ti–Al–Ta–Si–N coatings were studied using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nanoindentation. The chemical compositions of the coatings were Ti 0.41 Al 0.49 Ta 0.10 N and Ti 0.36 Al 0.44 Ta 0.10 Si 0.10 N. The x-ray diffraction investigation has revealed that both coatings had the B1-type FCC crystal structure. The microscopic studies showed that alloying of the Ti–Al–Ta–N coating with Si resulted in modification of their microstructure from pronounced columnar structure to predominantly fine-grain structure. The incorporation of Si was found to substantially enhance the hardness of the Ti–Al–Ta–Si– N coating compared with the Ti–Al–Ta–N one with simultaneous improvement of toughness.

The physical–mechanical properties (microhardness, Young’s modulus, plasticity characteristic, shape recovery ratio) of the synthesized layers of Ti–Ni–Nb-based surface alloys of ~2 μm thickness, formed on the surface of TiNi alloy by the additive thin-film electron beam metho d were investigated by the instrumented indentation. It was found that the change in physical–mechanical properties in the synthesized surface alloys based on Ti–Ni–Nb is due to their layered structure. In particular, it is due to the thickness of the sublayers, their phase composition, and the structural states of the phases (nanocrystalline and amorphous). It was established that high strength and elastic-plastic parameters of the outer layer and a monotonic change in the physical–mechanical properties from the surface to TiNi substrate are provided in the surface Ti–Ni–Nb alloy with a lower volume fraction of the amorphous phase in the synthesized layers. It was found that the multilayer structure of the surface Ti–Ni–Nb alloy and the monotonically change in the physical–mechanical properties to the substrate ensure high mechanical compatibility of the synthesized layers of surface alloys with the TiNi substrate.

Surface nanostructuring of Ti-6Al-4V titanium alloy samples in the process of electron-beam treatment and ultrasonic impact treatment have been studied using the methods of transmission electron microscopy and X-ray structural analysis. The effect of nanostructured surface layer of the Ti-6Al-4V titanium alloy on elastic recovery during scratch test, and, therefore, their wear resistance was demonstrated.

High-strength PI and PEI polymers differ by chemical structure and flexibility of the polymer chains that ensure lower cost and higher manufacturability of the latter. The choice of a particular polymer matrix is of actuality at design of antifriction composites on their basis. In this study, a comparative analysis of tribological behavior of PI and PEI- based composites was carried out with linear contact rubbing. The neat materials, as well as the two- and three-component composites reinforced with chopped carbon fibers, were investigated. The third components were typically used, but were different in nature (polymeric and crystalline) being solid lubricant fillers (PTFE, graphite and MoS2) with characteristic dimensions of several microns. The variable parameters were both load and sliding speed, as well as the counterface material. It was shown that an improvement of the tribological properties could be achieved by the tribological layer formation, which protected their wear track surfaces from the cutting and plowing effects of asperities on the surfaces of the metal and ceramic counterparts. The tribological layers were not formed in both neat polymers, while disperse hardening by fractured CF was responsible for the tribological layer formation in both two- and three component PI- and PEI-based composites. The effect of polymer matrix in tribological behavior was mostly evident in two-component composites (PI/CF, PEI/CF) over the entire P⋅V product range, while extra loading with Gr and MoS2 leveled the regularities of tribological layer formation, as well as the time variation in friction coefficients.

Ti-Al-Ta-N coatings are characterized by attractive mechanical properties, thermal stability and oxidation resistance, which are superior to ternary compositions, such as Ti-Al-N. However, because of their open columnar microstructure, the Ti-Al-Ta-N coatings deposited by conventional direct current magnetron sputtering (DCMS) exhibit insufficient wear resistance. This work is focused on obtaining the Ti-Al-Ta-N coatings with improved microstructure and mechanical and tribological properties by middle-frequency magnetron sputtering (MFMS). The coatings are deposited by the co-sputtering of two separate targets (Ti-Al and Ta) using pure DCMS and MFMS modes as well as hybrid modes. It is found that the MFMS coating has a denser microstructure consisting of fragmented columnar grains interspersed with equiaxed grains and a smaller grain size than the DCMS coating, which is characterized by a fully columnar microstructure. The modification of the microstructure of the MFMS coating results in the simultaneous enhancement of its hardness, toughness and adhesion. As a result, the wear rate of the MFMS coating is less than half of that of the DCMS coating.

The deformation behaviors of Ti-6Al-4V alloy samples with lamellar and bimodal microstructures under scratch testing were studied experimentally and using molecular dynamics simulation. It was found that the scratch depth in the sample with a bimodal microstructure was twice as shallow as that measured in the sample with a lamellar microstructure. This effect is attributed to the higher hardness of the sample with a bimodal microstructure and the larger amount of elastic recovery of scratch grooves in this sample. On the basis of the results of molecular dynamics simulation, a mechanism was proposed, which associates the recovery of the scratch grooves with the inhomogeneous vanadium distribution in the β-areas. The calculations showed that at a vanadium content typical for Ti-6Al-4V alloy, both the body-centered cubic (BCC) and hexagonal close-packed (HCP) structures can be more energetically favorable depending on the atomic volume. Therefore, compressive or tensile stresses induced by the indenter could facilitate β→α and α→β phase transformations, respectively, in the vanadium-depleted domains of the β-areas, which contribute to the recovery of the Ti-6Al-4V alloy subjected to scratching.