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We processed coarse-grained Ti and equal-channel angular pressing (ECAP) processed ultrafine-grained (UFG) Ti into 20-μm-thick Ti foils by cold rolling and intermediate annealing. The foils produced from rolling the UFG Ti exhibit a homogeneous nanostructure, while foils produced from rolling the coarse-grained Ti exhibit heterogeneous structures with a mixture of nanostructured regions and coarse-grained regions. The former foils also have higher strength and ductility and exhibit uniform deformation over a larger strain range at room temperature than the latter ones. This work demonstrated the advantage and viability of producing nanostructured Ti foil by rolling ECAP-processed UFG Ti stock.

A possibility to form submicrocrystalline structure in molybdenum using severe plastic deformation treatment by torsion under high pressure (HPT) at elevated temperatures has been studied. Quantitative parameters of grain–subgrain structure have been obtained by optical microscopy and transmission electron microscopy methods. Thermal stability of microstructure and mechanical properties have been studied. It is established that HPT results in the formation of a submicrocrystalline structure in Mo and in disappearance of residual porosity. The average grain size of HPT-Mo is 0.2 μm. The formation of submicrocrystalline structure enhances significantly (by 2.4 times) the microhardness of Mo relative to that in the as-received (before HPT treatment) state. It is found that grain growth begins at 1173 K and develops intensively at T ⩾1273 K.

The kinetics of the diffusion-induced recrystallization and its effect on creep resistance in a doped Ni3Al-based alloy is studied.

The Young’s modulus, internal friction, and microplastic flow stress in Cu-Nb nanolaminate has been determined by an acoustic technique. The influence of high hydrostatic compression (1 GPa) on these elasto-plastic properties of the nanolaminate has been studied.

The topography of the surface of the magnesium sample after irradiation by the high-intensity pulsed ion beam of a TEMP-4M accelerator was studied. The irradiation causes the formation of a regular comb structure and the creation of craters, their depth reaches 1-1.5 μm.

The structure and properties of a wrought Mg-Al- Zn-Mn alloy (MA5 brand) were characterized by SEM and direct pole figure (DPF). The crystallographic texture and strength anisotropy of the alloy subjected to unconventional thermomechanical treatment (lengthwise section rolling) clearly show marked improvement in its service parameters due to the formation of a fine-grained structure with low strain anisotropy. Keywords—wrought magnesium alloy; anisotropy of properties; crystallographic texture; thermomechanical treatment

Transmission electron microscopy is used to study the grain-subgrain structure of submicrocrystalline nickel produced by severe plastic deformation. The parameters of the grain-subgrain structure elements and the relative fractions of high- and low-angle grain boundaries in the microstructure subjected to severe plastic deformation are determined. The effect of the true grain size found by direct measurements on the mechanical properties of submicrocrystalline nickel is investigated.

Comparative investigations of diffusion in coarse-grained (d = 20 μm), nanocrystalline (d = 0.04 μm) and nanostructured nickel (d = 0.3 μm) have been carried out in a temperature interval of 0.2–0.3 melting temperature. The reasons for difference of parameters of copper grain-boundary diffusion in the above materials are discussed. The effect exerted by grain boundary state and grain boundary diffusion fluxes of impurity on creep mechanisms of nanostructured nickel and copper in the temperature interval of 373–473 K have been studied. Significant change in the apparent creep activation energy under copper grain boundary diffusion fluxes is described as a consequence of different contribution of grain boundary sliding to overall deformation.

High pressure torsion (HPT) was used in the present work to produce the metal matrix nanocomposite Cu+0.5 wt.% Al2O3. The mean grain size and root-mean-squared strain were studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD). It is shown that high ultimate strength (680 MPa) and microhardness (2300 MPa), as well as high thermal stability and electrical conductivity are features of the nanocomposite samples. Decrease of creep rate by one order of magnitude and increase of time to failure by a factor of 4–5 is revealed in the nanocomposite compared with the extruded sample.

The physicochemical properties of coatings produced by microarc oxidation on titanium alloys are investigated. The dependence of their structural and phase state on types of base alloys and electrolytic compositions is studied. The applicability of the titanium substrate-calcium phosphate coating system as a material for medical applications is substantiated.

The effects of ultrasonic surface treatment on the structural and phase-state of subsurface layers of polycrystalline and ultrafine-grained titanium are investigated. The changes in microhardness, mechanical properties, and regularities of microplastic deformation buildup are studied under static and cyclic loading. It is found that the characteristics of polycrystalline titanium suffer most from the ultrasonic treatment, while its influence on ultrafine-grained titanium is considerably weaker.

A study is conducted into the microstructure and physico-mechanical properties of ultrafine-grained titanium produced by severe plastic deformation using the method of equichannel angular pressing. The effects of thermal and mechanical treatment on these characteristics are investigated. The possibility of forming mechanical properties in titanium that compare well with those of highly doped titanium alloys is shown.

The osteoinductive characteristics of hydroxylapatite-based coating with different physicochemical characteristics were studied. The formation of the bone tissue on the studied types of the implant coating differed by the pattern and rate of formation of structural elements of the bone. Clear-cut phase-wise osteogenesis was seen on combined calcium phosphate coating: intense formation of the fibrous interstitial substance (due to cellular structure of hydroxylapatite) and slow maturing of cell elements. Bilayer composite coating provided (during the same period) the formation of more mature connective tissue. This phenomenon can be explained by better bioavailability of the coating material. The properties of combined calcium phosphate coating can be evaluated as mainly osteoconductive, while those of bilayer composite coating as osteoinductive.

We have studied changes in the isotopic composition of niobium and palladium as well as of titanium film structures over ceramics enriched in deuterium. We have also investigated changes in the isotopic composition of copper under thermally activated copper diffusion into nickel. An intense isotope exchange between the atoms of the matrices and impurities enriched in deuterium and changes in the isotopic composition of copper during diffusion into nickel were observed. The relationships seen in the experiments lead us to suggest that the changes in the isotope ratio may be caused (along with plausible nuclear transformations) by a strong isotopic effect involved in cold diffusion induced by hydrogen migration.

The depth-concentration profiles of nickel upon diffusion in submicrocrystalline (SMC) molybdenum processed by severe plastic deformation (SPD) have been studied by Auger electron spectroscopy. The coefficients (Db) and activation energies of the grain-boundary diffusion of nickel in SMC molybdenum were determined in a 973–1123 K temperature interval. The results indicate that a difference between the Db values in SMC and coarse-grained molybdenum is related to a nonequilibrium state of grain boundaries in the SPD-processed metal.

Kinetic mechanisms of phenomena to be induced by the diffusion on the grain boundaries in polycrystalline and nanostructured (NS) materials have been analyzed. By way of example of nickel and copper nanostructured (grain size 100÷300 nm) it was shown that the effect of diffusion induced loss of strength by creep was much observed at temperatures low than 400 K in comparison with polycrystalline condition with grain size 20 μm. It was supposed that the physical reason for the decrease in the temperature for the effect to manifest itself is much higher value of diffusion coefficients of impurities in nanostructures.

The possibility of realisation of superplastic state of nanostructured (NS) copper (grain size 0.1–0.3 μm) produced by equal-channel angular pressing has been studied during creep and tensile tests in vacuum and under the influence of aluminium grain boundary diffusion fluxes from external source (coating). The creep acceleration effect for NS copper under the influence of aluminium grain boundary diffusion fluxes is found. The effect takes place in a lower temperature range as compared with fine-grained copper. It has been established that at 473K strong increase of strain rate sensitivity (m = ∂ lgσ ∂ lg ϵ) takes place during deformation of copper under influence of aluminium diffusion fluxes (m = 0.5) in comparison with pure copper (m = 0.19)

The basic results from investigations of certain real problems in the physics of plasticity for single crystals and polycrystalline metal alloys carried out under the direction of the authors are given. The microdeformation patterns and formation of the flow limit in polycrystalline material are treated; the features of the mechanisms of deformation, deformational hardening, and the defect substructure in high-strength metal alloys are characterized. Analyses are carried out for phenomena involving activation of grain boundaries by grain boundary flows of impurity atoms, and experimentally based features of deformation on different structural levels under active extension, creep, and sign-alternating loading conditions. The main attention is given to the development of collective deformation modes. A discussion of some structural aspects of the realization of meso-level plastic flow with different deformation conditions is presented.

We have studied the creep of nickel and copper in a submicrocrystalline (SMC) state in a vacuum and in the presence of a diffusion contact with an impurity (Cu and Al, respectively). It is shown that a reduction of the resistance in the presence of a diffusion contact with an impurity is observed in the SMC materials in the temperature range 398 to 473 K. This range is 200 to 400 K lower than the corresponding range for coarse-grained material. It is shown that in this temperature interval the coefficients of grain boundary diffusion for copper in SMC nickel are 5 to 6 orders of magnitude larger than in the coarse-grained material. We propose that the reduction in the temperature for the manifestation of a creep activation effect in the presence of a diffusion contact with an impurity in SMC materials is caused by the increase in the diffusion permeability of the submicrocrystalline grain boundaries.

A study is made of the laws governing high-temperature creep and the evolution of the substructure in dispersion-hardened alloy Ni — 3 vol. % HfO2 during its free annealing and creep. The polygonized substructure was formed in the alloy prior to annealing. An analysis is made of structural transformations at different structural levels and the mechanism of high-temperature creep in the alloy.

Comparative investigations of the effect of diffusion streams of copper atoms (a weakly segregating impurity) and silver atoms (a strongly segregating impurity) from the surface in the high-temperature plastic deformation of nickel have been carried out. It has been established that in the high-temperature plastic deformation of nickel, when there are diffusion streams of copper and silver from the surface, there is a reduction in the creep resistance of nickel due to an increase in the contribution of grain-boundary slip to the overall deformation. Two stages, characterized by different values of the rate sensitivity factor m, are observed on the curve of the stress against the rate of deformation over a certain temperature range for each impurity. In the region of deformation rates of $$\dot \varepsilon< 2.5 \cdot 10^{ - 6} $$ sec−1, m≊0.2, and for $$\dot \varepsilon > 2.5 \cdot 10^{ - 6} $$ sec−1, m becomes less than 0.05.

The influence of femtosecond laser irradiation on the formation of an oxide layer on the surface of VT6 titanium alloy (Ti–6Al–4V) is studied. The structure, chemical and phase composition have been studied by x-ray diffraction, and scanning and transmission electron microscopy. The formation features of an oxide layer, which contains TiO2-rutile, TiO2-anatase Al2TiO5-aluminum titanate, Ti3O5-titanium oxide and TiO-titanium monoxide on the femtosecond laser-irradiation modified surface have been analyzed.

It is found that in aqueous 1% HCl solution, the electrochemical behavior of nanostructured titanium obtained by intense plastic deformation (equal-channel angular extrusion) insignificantly differ in the initial state and after the recrystallization annealing; subsequent slight deformations weakly affect the electrochemical parameters.

Two femtosecond laser nanograting fabrication mechanisms, including new ones recently found in our laboratory and related to sub-and near-threshold surface nanostructuring, are illustrated using experimental data for diverse solids nanostructured by 744-nm femtosecond laser pulses.

We have investigated the effects of surface copper diffusion on the creep of large-grain nickel (average grain size about 20 m) and submicron crystalline nickel (grain size about 0.3 m). For both structural states of nickel we find an acceleration of creep over its value in vacuum, and an increase in plasticity during creep when copper has diffused deeply into the nickel from the surface. The temperature range over which these effects are observed in the submicron nickel is nearly 300° lower than that for the large-grain samples. This result is probably due to a significant increase in the grain-boundary and bulk diffusion coefficients of copper in submicron nickel when compared with large-grain nickel.

Superimposed one-dimensional quasiperiodic gratings with multiple periods \ensuremath{\Lambda} \ensuremath{\approx} 110--800 nm well below or comparable to the pump laser wavelength of 744 nm, and ridge orientations perpendicular to the linear polarization of infrared femtosecond laser pulses, were fabricated after multiple near-threshold laser shots on a planar surface of quasimonocrystalline graphite in ambient air. The broad range of the grating periods corresponds to the large number of spatial Fourier harmonics of the final nanorelief (up to $m=7$th order, ${\ensuremath{\Lambda}}_{m}\ensuremath{\approx}800$ nm/$m=110--800$ nm), qualitatively representing the nonsinusoidal profile of the laser-induced intermediate surface relief (the set of periodic, broadly spaced narrow nanotrenches), which provides the corresponding multiangle diffraction of the incident femtosecond laser pulses. Experimental measurements and modeling of the transient optical constants of the photoexcited graphite justify the excitation, at the first stage, of the first-order (${\ensuremath{\Lambda}}_{1}\ensuremath{\approx}800$ nm) surface plasmon-polaritonic (SPP) wave on the photo-excited initial planar graphite surface becoming metallic via photo-generation of dense electron hole plasma ($\ensuremath{\sim}{10}^{21}$ cm${}^{\ensuremath{-}3}$). Such an SPP wave provides intermediate nanorelief in the form of the nonsinusoidal surface grating via its interference with the incident laser wave, resulting under near-threshold laser irradiation conditions in the highly localized surface ablation of the material in the interference maxima. During the next stage, the multiperiod subwavelength nanogratings develop through the multiangle diffraction of the multiple incident laser pulses on the intermediate nonsinusoidal surface grating.

Phase transformations of molybdenum under ion implantation with metal and gas ions have been studied by means of transmission electron microscopy. It is shown that, as a result of ion mixing of the surface-adsorbed gas elements of the ion source, thin (⩽ 100 nm) solid layers of the interstitial phases may be formed in the ion-implanted layers. The mechanisms of formation of the structure found are discussed by investigating the crystallographic details of phase transformations.

One-dimensional quasi-periodic structures whose period is much smaller than the wavelength of exciting optical radiation have been obtained on a titanium surface under the multi-shot action of linearly polarized femtosecond laser radiation at various surface energy densities. As the radiation energy density increases, the one-dimensional surface nanogratings oriented perpendicularly to the radiation polarization evolve from quasi-periodic ablative nano-grooves to regular lattices with sub-wavelength periods (90-400 nm). In contrast to the preceding works for various metals, the period of lattices for titanium decreases with increasing energy density. The formation of the indicated surface nanostructures is explained by the interference of the electric fields of incident laser radiation and a surface electromagnetic wave excited by this radiation, as shown by our transient reflectivity measurements and modeling, because the length of the surface electromagnetic wave for titanium with significant interband absorption decreases versus increasing electron excitation of the material.

The diffusion of nickel from the surface of polycrystalline molybdenum influences the crack formation and plastic deformation in creep. Investigation shows that diffusional fluxes of nickel from the surface reduce the critical deformation at which the first cracks appear in molybdenum. The contribution of grain-boundary slip to the deformation of molybdenum in creep is considerably increased in the presence of nickel diffusion from the surface as a result of easier crack formation and grain-boundary activation.

The dependence of the grain-boundary diffusion coefficient of nickel in molybdenum on annealing temperature was investigated. Possible causes are analyzed for differences in the values of the grain-boundary diffusion coefficients and the activation energies for this process from those obtained by earlier researchers.

The motion of individual HfO2 particles in a Ni-HfO2 alloy at T=1623 K is investigated. It is established that the velocity of particle motion V depends on their radius according to the law V ∼ r−3. The mechanism of particle motion in the given conditions is analyzed. It is shown that the mechanism controlling the mass transfer in particle motion is diffusion through the volume of the matrix.

Features of structurally-phase transformations in nanostructured and coarse grained (recrystallized) titanium in process of diffusion saturation by hydrogen in a wide interval of temperatures are studied.

The characteristic features of creep in nanostructured materials produced by severe plastic deformation have been studied at temperatures T < 0.3 Tmelt using nanostructured the Cu-0.5wt.%Al2O3 composite. The role of grain boundary state in plastic deformation development during creep is considered.

This article reports new experimental results on the mechanical behavior of the Ni48.9Ti51.1 alloy under shock‐wave loading in the temperature range from 213 to 413 K. The samples of NiTi alloy were loaded by impacts of aluminum flyer plates with a thickness of 0.4 mm and an impact velocity of 630±50 m/s. The increase in the yield strength from 0.4 to 2.7 GPa and the spall strength from 1.75 to 3.75 GPa Results indicate that in the range 213 K to 413 K, all values of the spall strength are higher than the values of austenitic NiTi alloys with high contents of nickel. The relationship Us‐up for martensitic NiTi demonstrated no anomaly that was observed with austenitic NiTi alloys.

The variation of the apparent creep activation energy as a function of the state of grain boundaries is investigated in the deformation of molybdenum in the presence of diffusion fluxes of nickel at the grain boundaries. It is shown that this energy varies in the same way as in the plastic deformation of classical superplastic materials.

The prospect of obtaining large volumes of materials with submicron grain size has become increasingly real. The equal channel angular (ECA) pressing appears to be among the most successful methods for producing such materials [1]. The structure of the materials obtained by this method has been the subject of intensive investigation [2–5]. In most cases the description of the structure of such materials has been qualitative. Recently detailed quantitative investigations of materials produced by ECA pressing, were reported [6, 7]. At the same time investigations of the structure of materials deformed by tension, compression, rolling and torsion up to great degrees of deformation have also become more quantitative as well (see, for example, [8–10]). For practical application of ultrafine-grained materials data on their structural stability is rather important. The later is closely connected, firstly, with the internal stress fields and, secondly, with the size distribution function for the substructure parameters [11]. Consequently, in such investigations the measurement of such parameters should be carried out statistically.

Severe plastic torsion straining was used in the present work for processing of the metal matrix Cu + 0.5%Al2O3 nanocomposite. The mean grain size, particle size distribution and elastic strain were studied by TEM and XRD. It is shown that high ultimate strength (680 MPa) and microhardness (2300 MPa) as well as high thermal stability and electrical conductivity are the features of the nanocomposite samples. The decrease of the creep rate by an order magnitude and the increase of the time to failure by a factor of 4–5 is revealed in nanocomposite as compared the extruded sample.

Nanostructured (NS) materials (grain size d ≤ 100 nm) are currently being intensively investigated. This special attention is due to the distinct physical, mechanical and other properties compared to when they are coarse-grained (CG) [1]. In particular, it has been found that diffusion coefficients (D) in NS materials exceed by several orders of magnitude the respective values in CG materials [2–4]. However, the physical reasons for the anomalously high values of D in these materials are debatable. The authors of [4] suggest that the self-diffusion in nanostructured Ni prepared by the inert gas condensation method occurs mainly along the boundaries of clusters and on the surface of pores located there. Clusters (having size 1–10 µm) consist of the complexes of nanoparticles having grain size d ≤ 100 nm. Diffusion along nanoparticles boundaries inside a cluster does not differ from grain boundary diffusion in CG materials, while diffusion along cluster boundaries closely resembles surface diffusion.

The practical application of nanostructured materials obtained by severe plastic deformation involves two main problems at least. Firstly, there is the instability of non-equilibrium structure connected with high energy accumulated by severe plastic deformation [1]. The instability is the reason for intense softening at relatively low temperature. This temperature is close to room temperature for several nanostructured materials, for example, copper [2]. Secondly, there is the increased diffusivity of nanostructured material state. This leads to high sensitivity to the influence of surrounding. One of the most important type of this action is grain boundary fluxes from an external source, for example, coating [3, 4].