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Extension of life of steam pipelines, operated under creep conditions, determines the necessity of evaluation of their damageability and in many respects depends on carbide transformations in metal. The work considers peculiarities of diffusion and structure of carbide phases in metal of welded joints of pearlite steels after long-term operation. It is determined that concentration of coagulating carbide phases (M23C6, M7C3 etc.) at the boundaries of α-phase grains promotes for nucleation of creep pores and fatigue cracks, that causes brittle fracture of metal of welded joints. [ABSTRACT FROM AUTHOR]

Laws of the structure formation, as well as the strength properties and thermal stability of vacuum condensates of the Fe-W system have been studied. It has been found that the alloying of iron foils with tungsten to 1 at % makes it possible to disperse the grained structure of the condensates to nanometric dimensionality and to markedly enhance their strength properties and recrystallization temperature. Thus, the foils containing ∼0.8% tungsten and grains of about 50 nm in size exhibit the hardness 5.5 GPa and recrystallization temperature 800°C. These results can be used to devise compositions of the steels designed for subsequently obtaining high-strength and thermostable nanostructural states. [ABSTRACT FROM AUTHOR]

Nanocomposite films based on (Nb2Al)N intermetallic nitride have been obtained by the method of magnetron sputtering. X-ray diffraction analysis revealed two stable states of the crystalline structure: (i) NbN with low amount (within 5 at %) of dissolved Al in a composition close to (NbAl)N and (ii) an amorphous component related to aluminum nitride formed by reactive magnetron sputtering. The substructural characteristics (grain size and microdeformation level) are sensitive to the current via Al target and exhibit correlation with nanohardness and Knoop hardness of the film, which vary within 29-33.5 and 46-48 GPa, respectively. [ABSTRACT FROM AUTHOR]

Results of studies of the morphology, elemental and phase compositions of coatings prepared by pulsed magnetron sputtering of the AlN-TiB-TiSi composite ceramic target have been reported. The used technology allows us to prepare a protective amorphous-like layer with ordering areas with sizes up to 1 nm. The heat treatment of samples at 900 and 1300°C leads to the depletion of the coating surface of boride phases and the formation of α-AlO- and β]-TiO-based protective films on the surface. The growth of crystallites of the nanostructured coating to 11-25 nm is observed. The annealing at 1300°C allows us to obtain the thermally stable crystalline state of substance, the nanohardness of which is 11 GPa. [ABSTRACT FROM AUTHOR]

The effect of the high-voltage supply capacity in the form of different pulse duration on the formation of preferentially oriented crystallites and the stress-strain state of the vacuum-arc TiN coatings was analyzed. It is shown that the deposition of coatings in a high-voltage cascade forming exposure leads to the growth of the crystallites with axis texture [110] and the change in the stress-strain state: strengthening of a strain in a group of crystallites with the axis [110] and reduction of the strain in a group of crystallites with axis [111]. The results are explained by the increase in mobility of atoms and streamlining processes in the field of displacement cascades, formed under the influence of high-energy bombarding ions accelerated in the field of high-voltage pulse potential. A generalized graph of the texture type on the pulse potential and influence of the pulse duration, applied to the substrate, on the total deposition time are plotted. [ABSTRACT FROM AUTHOR]

The mechanical characteristics of the multi-element coatings (TiNbCrZrSi)N have been studied depending on the deposition process parameters, in particular the bias potential. X-ray diffraction spectra has shown, that the coating is formed on the basis of single-phase state of the fcc lattice, which in the case of nitrides has structural type NaCl. Hardness and elastic modulus of the coating (TiNbCrZrSi)N varies from H = 24 GPa and E = 254 GPa to H = 28.9 GPa and E = 291 GPa. Coatings' index of resistance to plastic deformation (H3/E2) has a value of 0.28. [ABSTRACT FROM AUTHOR]

Influence of constant and pulsed negative bias potential applied to the substrate during the deposition on the phase composition, structure, substructure and mechanical properties of multilayer ZrN / TiN coatings with a bilayer thickness of 50-200 nm was studied. Two-phase coating obtained from ZrN and TiN phases of the fcc structure of NaCl type without a significant loss of planarity and mixing layers is established. The use of high-voltage pulses would greatly change the structure and properties at Ub < 100 V. At larger value of Ub, constant potential becomes crucial for the structural engineering of the coating. It is shown that the greatest hardness is inherent to the coatings obtained by Ub = - 140...- 150 V, and H/E reaches a large value of 0.14, which is difficult to obtain in the single-layer coatings. [ABSTRACT FROM AUTHOR]

Structure and properties of (Zr-Ti-Cr-Nb)N multicomponent nanostructured coatings fabricated by a vacuum-arc deposition have been investigated. It has been found that the coatings thickness attained 6.2 μm, hardness and indentation load that is responsible for the stress exceeding cohesion strength of coatings were H = 43.7 GPa and L = 62.06 N, respectively. In coatings structures have been identified that consist of three interstitial phases having cubic, hexagonal, and tetragonal lattices. The nanocrystallites sizes were from 4 to 7.3 nm. The results of the SEM, TEM, EDS, and XRD analysis have been also considered. [ABSTRACT FROM AUTHOR]

Frictional properties of multi-element nanocomposite coatings by means of tribometry method have been studied. The obtained nitride nanostructured coatings include only a single phase of solid solution with the fcc lattice and NaCl structural type with (111) preferred orientation. The influence of annealing temperature on the tribological characteristics has been studied. It has been determined that the wear resistance (wear factor) of the coatings after annealing was 1.03 ×10-5 mm3 N -1 m -1 which is higher than before the annealing 7.8 10 -5 mm3 N -1 m -1. [ABSTRACT FROM AUTHOR]

By the X-ray diffraction, electron microscopy, and microindentation methods we have investigated the phase composition, structure, substructure and hardness of vacuum arc multilayer coatings of TiN / CrN system obtained in the range of nitrogen pressure of 1·10-5 ... 5·10-3 Torr when applying continuous and pulsed negative bias potential. Formation of two-phase state with a preferred orientation of the crystallite growth was established at high pressure of (1 ... 5)·10-3 Torr and feeding of negative DC bias potential: Ub = - 20 V - texture axis [100], at - 230 V - texture axis [111]. Based on the studies of substructural state, connection of the transition to the superhard (57 GPa) state with decrease in the crystallite size and microstrain in TiN layers was established. [ABSTRACT FROM AUTHOR]

The questions of structural engineering of Cr-N system coatings produced by vacuum arc evaporation of Cr cathode in a nitrogen atmosphere are considered. As the variable physical and technological parameters we have used the following ones: pressure of nitrogen atmosphere (3.5-48) 10-4 Torr and negative bias potential applied to the substrate in constant (Ub= - 120 V) and pulse (Uip= - 1200 V) modes. Increase in the pressure without pulse action allows to transfer from Cr + Cr2N phase to phase of textured CrN crystallites with [111] axis. The transition from the metallic phase to the mechanical nitride is accompanied by a decrease in the average size of crystallites. Additional supply of impulse capacity allows to intensify the process of formation of nitrides and stimulates formation at high pressure of radiation resistant texture units with the [110] axis. [ABSTRACT FROM AUTHOR]

Results of comprehensive investigations of nanostructed TiN and MoN single-layer coatings as well as multilayer coatings consisting of TiN/MoN alternating layers have been considered. The coatings have been deposited by a promising modern method of cathode-arc evaporation (vacuum-arc method). The elemental and phase compositions of coatings, their tribological and physico-mechanical properties: friction coefficient, wear, adhesion, hardness, and elastic modulus have been studied and the mechanisms of the coatings fracture have been discussed. [ABSTRACT FROM AUTHOR]

This paper presents the results of investigation multilayer TiN / MoN coatings. Coatings were fabricated using Arc-PVD method. Period thickness of nanoscale layers in coatings was λ = 8, 25, 50 and 100 nm. The total thickness of coatings was up to 8.4 μm. Samples were studied using SEM, TEM, EDS, RBS, XRD, SIMS and nanoindentation. The actual thickness of the layers has a few larger values than expected (in most cases per 25 %). The formation of two phases was found: stoichiometric TiN (fcc) and cubic γ-Mo2N (fcc). Maximum values of hardness and elasticity modulus were obtained for coating with λ = 8 nm: H = 47 GPa, E = 470 GPa. Plasticity index and its dependence on the thickness of layer period (λ) were calculated. The most plastic coating was the sample with H / E = 0.1. [ABSTRACT FROM AUTHOR]

In order to develop the direction of "structural engineering nitride coatings" in the work conducted systematic analysis of the impact of the negative bias potential (direct and high-voltage pulse) on the structure, substructure and mechanical properties of ZrN coatings obtained by vacuum arc evaporation. Defined boundary value of (– 100 V) DC potential applied to the substrate, below which a high-voltage pulse potential (– 1200 ... – 2000 V quantity that allows to form peaks bias) makes a decisive contribution to the formation of preferred orientation of the crystallites with the [110] axis. The highest values of hardness 43 GPa are achieved at a constant potential -70 V. Supply high-voltage pulse shifts the maximum hardness in the direction of a greater value of the constant potential. [ABSTRACT FROM AUTHOR]

Coatings based on (Ti-Zr-Nb)N were obtained by means of vacuum-arc deposition method. Their physical and mechanical properties, as well as tribotechnical characteristics have been studied. The coefficient of friction of the system "coating-Al2O3" is 1.1. The coatings are characterized by a columnar structure and their hardness reaches HV0.05 = 44.57 GPa. [ABSTRACT FROM AUTHOR]

The influence of the structural state (by X-ray diffraction data) on the resistance to abrasive wear of titanium nitride (TiN) coatings obtained by vacuum-arc deposition at nitrogen pressures within (1-67) × 10 Pa at a constant negative bias potential of −230 V with and without additional stimulation by high-voltage pulses. The abrasive wear resistance was evaluated by the ball-cratering technique. It is established that the dependence of the wear resistance of arc-deposited TiN coatings on their structural state is not determined entirely by the degree of texturing. This is a multifactor process, and the main factors are the formation of nanosized crystalline grains and the macroscopically deformed (compressed) state of coatings with a strain level of −1.8 to −1.9%. [ABSTRACT FROM AUTHOR]

The influence of the deposition temperature of TiC-WC quasi-binary system ion-plasma coatings (magnetron scheme) of different composition is investigated. The substantial expansion of the probable structural and substructural states under nonequilibrium conditions of receiving a material from ion-plasma fluxes is demonstrated. The composition changes from monophase (Ti, W)C to two-phase (Ti, W)C and α-W2C, the structure - from the nontextured one to the texture with the axes [111], [100] or [110]. The type of the texture depends on the deposition temperature and composition. When the state on the substructural level is monophase the increase of the substrate temperature leads to the increase in the size of crystallites and microstrain reduction. Creating the second phase determines opposite effects - reduce the size of the crystallites coverage and increase microstrain. [ABSTRACT FROM AUTHOR]

The effect of the pressure of the nitrogen atmosphere during the formation of vacuum arc nitride coatings based on high entropy alloys of the Ti-Zr-Hf-V-Nb-Ta system on their structure, hardness, and tribotechnical characteristics is considered. It is shown that strong nitride-forming components lead to the dependence of the structural state and properties on the pressure of the nitrogen atmosphere during coating deposition. Deposition at a nitrogen pressure of 0.4 Pa results in the formation of a texture with the [111] axis when the applied bias potential is −70 V and when the bias potential is equal to −150 V the textural structure is biaxial ([111] and [110]) textures and high value of hardness of 51 GPa Along with that the highest value of wear resistance (under oxidizing-mechanical wear) is inherent to coatings formed under the pressure of nitrogen of 0.09 Pa. The strongest microdeformation of coating crystallites corresponds to this pressure. [ABSTRACT FROM AUTHOR]

AlN-TiB composite ceramic samples with a TiSi additive are obtained by magnetron sputtering. After deposition, ordered regions in the coatings measure 1 nm across, so that they can be categorized as amorphous-like. Annealing at 900 and 1300°C causes crystallization with grain sizes of 11 and 25 nm, respectively. However, crystallization does not dramatically deteriorate the mechanical properties owing to the formation of high-enthalpy phases (AlB at 900°C and AlB at 1300°C). The hardness of the coatings varies from 15.1 GPa in the as-prepared samples to 11.0 GPa after annealing to 1300°C. This makes it possible to improve the wear resistance of edge tools with these coatings by a factor of 1.32 at a temperature of 1300°C near the contact. [ABSTRACT FROM AUTHOR]

Current paper presents the results of investigating of nanostructured cathode arc vacuum evaporation coatings, based on (Ti, Hf, Nb, Si)N. Several methods of the structural and elemental analysis were used: proton microbeam, nano- and micro-electron beam, X-ray diffraction analysis. To determine tribological properties (scratch resistance, adhesive and cohesive strength) of the coatings, scratch testing were conducting. Influence of thermal annealing at temperatures 300, 500, 800, 1000 °C on elemental composition, microstructure, residual stress, phase composition, profiles of atomic distribution in the coatings were investigated. [ABSTRACT FROM AUTHOR]

The coatings investigated in this paper were deposited via the magnetron sputtering of AlN-TiB2-Ti-Si2 target in Ar atmosphere. The investigation of structural-phase composition, element composition, morphology and mechanical properties before and after annealing up to 1350°C was carried out. The concentration of elements in the coating was changed after annealing at 900 °C and further annealing at 1350 °C (especially after annealing at 1350 °C). The hardness of as-deposited coatings was 15 GPa, but after annealing at 1350°C the value of hardness increased up to 22 ÷ 23.5 GPa. The value of the viscoplastic index was 0.07. All this provide high damping properties of the coating, and amorphous-like structure makes promising the use of these coatings as diffusion barriers in the form of independent elements, and as a contacting layer in multilayer wear resistant coatings. [ABSTRACT FROM AUTHOR]

The regularities of the formation of ion-plasma coatings of Ti-W-B system and the impact of postcondensation treatment on their phase composition, structure, substructure and stress state. It is shown that at a low content of Ti-component (up to 2 at.% ) two-phase state from β-WB- and (Ti, W)B2- phases is formed. Annealing at 1270 K leads to the grain growth of the β-WB-phase mainly. When the content of Ti is more than 5 at.%, a single-phase (Ti, W)B2 state of the coating is formed. Structure and substructural characteristics of these coatings are stable at annealing and proton irradiation with the energy of 200 keV up to the dose of 6,5·1017 cm–2. Influence of thermal-radiation exposure affects the change of the stressstrain state (relaxation of compressive strain). The observed changes are explained on the basis of minimizing the free energy of the system. [ABSTRACT FROM AUTHOR]

The effect of nanolayer thickness on the structure and properties of nanocomposite multilayer TiN/MoN coatings is revealed. The multilayer (alternating) TiN/MoN coatings are prepared by the Arc-PVD method. The selected thickness of the nanolayers is 2, 10, 20, and 40 nm. The formation of two phases-TiN (fcc) and γ-MoN-is found. The ratio of Ti and Mo concentrations varies with varying layer thickness. The maximum hardness value obtained for different thicknesses of the layers does not exceed 28-31 GPa. The stability of TiN/MoN during cutting and tribological tests is significantly higher than that of products with TiN coatings. The nanostructured multilayer coatings with layer thicknesses of 10 and 20 nm exhibit the lowest friction coefficient of 0.09-0.12. [ABSTRACT FROM AUTHOR]

Multicomponent hard coatings based on nitrides of Si-doped transition metals have been produced by vacuum-arc deposition with the use of a RF generator and separation of an ion-plasma flux. Physico-mechanical and tribotechnical characteristics of coatings have been studied. The possibility of their use as efficient protective coatings has been shown. [ABSTRACT FROM AUTHOR]

Three series of Al 2O 3 coating samples are fabricated by microarc oxidation under various deposition conditions and are studied by scanning electron microscopy (SEM) in combination with energy-dispersive x-ray spectroscopy (EDXS), Rutherford backscattering, and X-ray diffraction. Defects and pores in the coatings are analyzed by positron annihilation spectroscopy at room temperature without vacuum. No nanometer pores are detected in the coatings. When changing the electrolyte-plasma oxidation conditions, one can change the concentration and the ratio of the types of vacancy defects in these Al 2O 3 coatings. [ABSTRACT FROM AUTHOR]

Nitrides of high-entropy alloys TiZrHfVNb produced using a vacuum-arc cathode evaporation have been studied using scanning electron and atomic force microscopies, energy dispersive, Rutherford ions backscattering, and X-ray diffraction analyses, microhardness measurements, and tribological tests. It has been found that the deposition parameters affect the structure, surface morphology, distribution of elements, mechanical and tribological properties of the coatings under study. [ABSTRACT FROM AUTHOR]

Multicomponent nanostructured (Ti-Zr-Hf-V-Nb)N coatings produced by the cathodic-arc-vapor-deposition method have been studied using several complementary methods of elemental and structural analysis, such as those based on the use of slow positron beam (SPB); proton microbeam (μ-PIXE); electron micro- and nanobeam (EDS and SEM analysis); and X-ray diffraction phase analysis (XRD), including the a-sinϕ method of measuring the stress-strain state (X-ray tensometry). The elemental composition, microstructure, residual stresses in nanograins, and in-depth and surface distributions of defects and atoms, as well as the phase composition, stress-strain state, and texture of the coatings have been studied in a 3D representation. It has been found that creating a state of elastic stress-strain compression in the coating can significantly enhance its resistance to oxidation upon annealing. A redistribution of elements and defects (their aligning and segregation) due to diffusion and termination of spinodal segregation has been revealed near interfaces, around grains and subgrains, which occurred without a significant change in the average size of nanograins. [ABSTRACT FROM AUTHOR]

Arc vacuum deposition of nitride coatings in the Ti-Si-N system is carried out in an argonnitrogen mixture with variable gas concentration ratios. The resulting condensates are studied by fractographic analysis, X-ray diffraction analysis, and high-resolution scanning electron microscopy. Studied also are the elemental composition and microhardness of the condensates. At gas mixture pressure p > 5 × 10 Torr, conditions are found under which the hardness of the condensates is maximal, and the dependence of the hardness on the argon percentage in the mixture is obtained. At an argon percentage of 8-12%, the hardness of the coatings reaches 50 GPa. This value is 1.7 times higher than the hardness of coatings obtained in a nitrogen atmosphere. This superhard state is explained by the nanometer size (25-30 nm) of nitride grains and a specific growing texture with a family of {100} planes that is parallel to the growth plane. Such a configuration minimizes the surface energy. Mechanisms that may increase the ionization of film-forming particles and activate chemical bonds in the presence of argon are discussed. [ABSTRACT FROM AUTHOR]

Two complementary X-ray diffraction schemes with orthogonal diffraction vectors are proposed to study the structural state of ion-plasma coatings of the quasi-binary Ti-W-B system: one with a diffraction vector oriented parallel to the normal to the coating surface and the other with a diffraction vector oriented perpendicular to the coating normal (i.e., parallel to the growth surface plane). This technique made it possible to reveal and investigate the anisometry of crystallites at different temperatures and thicknesses of the layer formed, as well as to analyze the strained state. Models are proposed to describe the revealed regularities of crystallite growth. [ABSTRACT FROM AUTHOR]

The tribological characteristics of nanocomposite Ti-Hf, Ti-Hf-N, and Ti-Hf-Si-N coatings deposited by the pulse HF-assisted vacuum arc method are studied. A substantial increase in the wear resistance and a decrease in the coefficient of friction of a protective Ti-Hf-Si-N coating compared to the steel substrate and protective Ti-Hf and (Ti, Hf)N coatings are found and explained. [ABSTRACT FROM AUTHOR]

The reproducibility of the single-phase structural state of the Ti-V-Zr-Nb-Hf multielement system (a high-entropy alloy) is demonstrated using the vacuum-arc method to prepare coatings based on this system. Single-phase high-entropy compounds with a bcc lattice typical of the molten state result from vacuum deposition; preparation in nitrogen atmosphere yields single-phases nitride superhard nanocrystalline coatings based on the fcc metallic lattice. [ABSTRACT FROM AUTHOR]

The effect of the conditions of deposition of vacuum-ac multilayer TiN/Ti coatings on their phase composition, structure, stress state and mechanical properties is investigated. Regular features of variation of the phase composition, structure-and-stress state and hardness as a function the value of the negative potential applied to the substrate during the deposition and on the thickness of the Ti and TiN layers in the multilayer coating are determined. The causes of the observed changes are analyzed using the mechanism of formation of surface layers of the vacuum-arc coatings under the conditions of the implantation processes stimulated by application of negative potential to the substrate. [ABSTRACT FROM AUTHOR]

Superhard nanostructured Ti-Hf-Si-N coatings (films) possessing high physical and mechanical properties have been produced. Nuclear and atomic physical analyses, such as RBS, SIMS, GDMS, SEM-EDXS, XRD, and nanoindentation were used to investigate the elemental and phase composition and the morphology of the films as functions of the pressure in the chamber and of the bias voltage applied to the substrate. It was observed that as the grain size in nc-(Ti, Hf)N coatings was decreased from 6.7 to 5 nm and α-SiN (amorphous or quasi-amorphous phase interlayer between nanograins) formed, the coating nanohardness increased from 42.7 to 48.4 ± 1.6 GPa. However, the further decrease of the (Ti, Hf)N grain size to 4.0 nm resulted in a slight decrease in nanohardness. The stoichiometry of the films changes from (Ti-Hf-Si)N to (Ti-Hf-Si)N, and also changed the lattice parameter of the (Ti, Hf)N solid solution. It should be noted that the high-hardness coatings showed the least friction coefficient (0.2), and its value remained unchanged until the coating worn out. [ABSTRACT FROM AUTHOR]

The effect of substrate bias on the structural-phase and elastic stress-strained state during the formation of vacuum-arc-deposited nanostructural coatings of the Mo-N system has been studied. An increase in the bias potential leads to (i) predominant [111] orientation of the growing molybdenum nitride crystals with a NaCl-type cubic lattice (γ-MoN phase) and (ii) the appearance of a second phase with a body-centered cubic crystal lattice that is characteristic of pure molybdenum. The elastically strained (stressed) state of the coating is determined not only by the conditions of deposition, but also by the mechanical properties of a substrate. In order to provide for formation of coatings in a high-elastic-strained (stressed) state, it is necessary to deposit coatings onto substrates with high elastic moduli, which prevent metal flow at the interface. These highly stressed coatings with grain sizes within 9-14 nm possess high hardnesses that reach up to 45-50 GPa. [ABSTRACT FROM AUTHOR]

Regularities of the formation of the phase and structural state and mechanical characteristics of vacuum-arc coatings produced by the evaporation of Zr-Ti-Si-N targets in a reactive nitrogen atmosphere have been studied. For the targets of compositions Zr 92.0 wt %, Ti 3.9 wt %, Si 4.1 wt %, and Zr 64.2 wt %, Ti 32.1 wt %, Si 3.7 % at a working pressure of the nitrogen atmosphere of 0.1-0.8 Pa and a potential at the substrate of −100 and −200 V, the formation of a single-phase crystalline state of the coatings (nitride of the solid solution of the components of the target) has been established. The size of crystallites is in the nanometer range (25-85 nm). An increase in the size of crystallites in the direction of the incidence of the film-forming particles (perpendicular to the growth plane) is favored by an increase in the bias potential from −100 to −200 V. The low heat conductivity of the metallic (Ti and Zr) components of the target leads to a significant content of a droplet phase when using the direct-flow regime of the vacuum-arc deposition and requires the employment of a technological scheme with a separation of the film-forming beams to increase the homogeneity of the high mechanical properties of the coatings. The use of film-forming beams separated from the droplet phase makes it possible to increase the homogeneity of the surface morphology of the coatings with the retention of a large index of plasticity ( H/ E = 0.8-0.9) and high hardness (33-37 GPa) of the material of the coating. [ABSTRACT FROM AUTHOR]

The effects of trapping of ion-implanted deuterium and its thermal desorption on the structure and stressed state of a tungsten coating deposited on a composite substrate is studied. The amount of accumulated deuterium, macrostresses of the coating, and the shape of thermal desorption spectra are shown to depend on the D ion fluence and the irradiation temperature. Possible mechanisms of these processes are proposed. [ABSTRACT FROM AUTHOR]

Small-angle X-ray scattering is used to study the effect of deposition and annealing conditions on the concentration-structure ordering in ion-plasma W-Ti-B condensates. At a relatively low condensation temperature of a solid solution (up to Tc = 770 K), the formed modulated structure has a uniform volume distribution of its structural elements. A stage-by-stage transition from a volume-modulated to a two-dimensional modulated structure is revealed when the condensation temperature increases from 570 to 1170 K. As the annealing time of the metastable postcondensation state of an ion-plasma condensate increases, the diffusion mobility of metallic atoms (W, Ti) decreases upon the formation of a modulated ordered structure. The action of a radiation factor in a three-electrode ion sputtering scheme enhances the concentration phase separation in a condensate, decreases the transition temperature, and stimulates an increase in concentration ordering wavelength λod. [ABSTRACT FROM AUTHOR]

The dependence of elastic moduli for different directions on the nonstoichiometry with respect to carbon atoms in octahedral interstices of face-centered cubic crystalline lattice is established for the first time for metastable tungsten carbide (β-WC phase). It is shown that with decreasing content of carbon atoms in the tungsten carbide lattice it is compressed, which is accompanied by the growth of the contribution of metallic component, thus determining higher density of the coating material and change of elastic characteristics for different crystallographic directions. This makes it possible to obtain carbide coatings with the required ratio of elastic constants via corresponding technological regimes, which is especially important in formation of coatings with predominant crystallite growth orientation. [ABSTRACT FROM AUTHOR]

The possibilities of structural engineering in multiperiod TiN/Ti, TiN/CrN, TiN/MoN and TiN/ZrN systems are presented. Three principal parameters determining the structural state and properties of the coatings are determined, i.e., the substrate potential during the deposition, the thickness of layers in a period, and the pressure of the working atmosphere. The results of the study are used to develop deposition modes providing high mechanical properties in the coatings. [ABSTRACT FROM AUTHOR]

The possibility of obtaining hard nanocrystalline coatings using vacuum-arc deposition in a high-frequency discharge stimulated regime has been studied. Condensates of the Zr(Ti)-Si-N system obtained by this method contain ZrN and TiN crystalline grains. These grains exhibit a compressive strain of about −1.1% in the film growth plane, which corresponds to compressive stresses up to about 3.5 GPa in the film-substrate system. The results of nanoindentation show evidence for a strong inhomogeneity of the coatings, in which regions possessing a hardness of 29–30 GPa alternate with those where the hardness exceeds 45–47 GPa. This pattern agrees with a two-phase model based on the structural data, according to which the condensed material consists of less hard ZrN grains and harder TiN grains. [ABSTRACT FROM AUTHOR]

First results in the field of synthesis and research of the multicomponent (Ti-Zr-Hf-V-Nb)N nanostructured coatings are presented in the paper. Influence of processes of spinodal segregation and mass-transfer on single-layered or multilayered crystal boundary (second phase) forming were explored. Superhard nanostructured coatings were investigated before and after annealing at the temperature 600 °C using unique methods (slow positron beam, proton microbeam particle induced X-ray emission-µ, Rutherford backscattering-analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction analysis was performed using DRON-4 and nanoindentor). Diffraction spectra were taken point-by-point, with a scanning step 20 = 0.05 to 0.1°. We detected that positron trapping by defects was observed on the nanograins boundaries and interfaces (vacancies and nanopores which are the part of triple and larger grain's boundary junction). The 3D distribution maps of elements obtained by the proton microbeam (particle induced X-ray emission-µ) together with the results obtained by slow positron microbeam gave us comprehensive information about physical basis of the processes, connected with diffusion and spinodal segregation in superhard coatings. [ABSTRACT FROM AUTHOR]