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The effect of average grain size on the mechanisms of polycrystal deformation are considered in the range of grain sizes from 1nm to 1cm. Critical grain sizes are selected. The activity of dislocation and diffusion mechanisms is analyzed. The deformation distribution in grains of different sizes is considered for a polycrystal as a whole within the grain size distribution.

The paper considers the influence of size effects on dislocation structure and second-phase particles. Particular attention is given to scalar dislocation density, geometrically necessary dislocation density and parameters of particles formed at grain boundaries. It is found that there exist three critical grain sizes in the range of which the mechanisms of deformation and hardening of polycrystals are changed. Special emphasis is placed on stabilization of the submicropolycrystal grain structure by second-phase particles present at the grain boundaries.

The structural state of the γ′ and γ phases of modern superalloys is considered in detail. A classification of the scale effects in the γ′ phase morphology is proposed.

Phase composition, thin structure and morphology of the surface of the intermetallic coating are investigated by transmission electron microscopy, X-ray analysis and atomic force microscopy. It is shown that Ni 3 Al is the main phase of the intermetallic coating for all investigated samples. There is a small amount of the NiAl and AlFe 3 C phases. The application of temperature and ion beam treatment changes the atomic long-range order parameter and the elastic microstresses of the crystalline lattice.

The paper presents the results of the transmission electron microscopic (TEM) investigation of the structure and phase composition of nanocrystalline copper obtained by the severe plastic deformation using the high pressure torsion (HPT) method. Special attention is paid to the triple junctions of grain boundaries. It was established that the triple junctions contained the partial disclinations and particles of the secondary phases. The dependences of such junction fractions on the deformation were measured of the formation at nanocrystalline copper. The phase analyses of the secondary phase structure were carried out, the sizes of the phase particles and their volume fractions were determined. The bending – torsion of the crystal lattice arising near the triple junctions was measured. The problem of the long – range stress field screening was considered.

A quantitative analysis of the evolution of the dislocation cell substructure during the deformation of face-centred cubic metals and alloys is presented. Particular features are distinguished in the behavior of pure metals and solid solutions with different states of atomic order. The influence of temperature and grain size on the main substructural parameters is studied. It is established that the dependence of cell size on dislocation density becomes less pronounced when going from single crystals to polycrystals with large and small grain sizes. An increase in deformation temperature is shown to have the same effect. The relationship between cell size and the width of cell walls is also examined.

The paper presents the transmission and scanning electronic microscope investigations of Ni-Al-Cr superalloy alloyed with additional Re and La elements. This superalloy is obtained by a directional solidification method. It is shown that such additional elements as Re and La result in formation of new phases in Ni-Al-Cr accompanied by considerable modifications of quasi-cuboid structure in its γ’-phase.

The regularities of the formation of the structure of silumin irradiated with a high-intensity electron beam in different modes are revealed using optical and scanning electron microscopy. The optimum irradiation mode that allows one to increase the fatigue life of this material by a factor of up to 3.5 is determined. The probable causes of the observed effect are investigated.

The article deals with the influence of surface treatment of substrates by copper ions on the structure and phase composition of nanocomposite coatings. The coatings were sputtered on titanium substrates by Cu ions using a KVANT-03MI installation. Investigations were carried out by X-ray, TEM and SEM methods. It was established that intermetallics of the Cu–Ti system were formed in the surface layer of the substrates. It was found that phase composition and surface morphology were dependent on duration of the ion treatment.

The method of diffraction electron microscopy is used to study the influence of the tempering period on the defect structure of the Fe-0.38C-3.5Ni-1.3Cr-0.24Si-0.35Mn-0.4Mo-0.15V-0.3Cu cast construction steel. It is demonstrated that tempering causes the substructural nonfragmented → fragmented substructure transformation, which is the main substructural transformation. Three types of fragments are formed, including initial and anisotropic secondary fragments with network and cellular dislocation substructures and tertiary isotropic dislocation-free fragments. The fragmentation process at tempering is accompanied by a continuous decrease in the scalar dislocation density.

The structure and phase content of a weld in Fe–0.09C–2Mn–1Si steel are investigated by the methods of transmission electron microscopy (TEM) and metallography. A gradient weld structure is established. The manner in which the phase content of steel, the ferrite and pearlite grain sizes, and the morphology of cementite particles depend on the increasing distance from the weld center is elucidated.

The methods of transmission electron microscopy are used to investigate the structure and phase content of Fe–0.45C–17Mn–3Al steel subjected to multicyclic fatigue tests to failure after intermediate electrostimulation. It is demonstrated that electrostimulation does not change the mechanism of steel failure. An increase in the operating life time of samples after electrostimulation in the intermediate test stage is connected with the hindered γ → e-martensitic transformation, the relaxation of stress concentrators, and the reduction of the volume fraction of the critical dislocation (network) substructure in which e-martensite is mainly developed.

The phase and structure transformation of tempered martensitic steel in the course of plastic deformation is considered in the present paper. A close correlation between the evolution of the substructure type and the behavior of carbon is established. The carbon concentrations in solid solution and on crystalline defects of the material as a whole and in different dislocation substructures are investigated versus the degree of plastic strain.

The phase composition and fine structure of intermetallic coatings are investigated by electron microscopy and X-ray analysis. It is shown that intermetallic Ni3Al is the main phase of the coating for all samples under study. Ion implantation of coatings with aluminum and boron ions leads to changes in the lattice parameter and the parameters of long-range order, internal elastic stress, grain size, and dislocation structure.

The technique and results of an experiment on the deformation of nitrided steel Cr18NMn15 are described. Within the framework of the model proposed, the factors stabilizing the 4H structure and their role in the strain dependence of the 2H and 4H structure fractions are identified. It is shown that the appearance of the 4H structure in the fcc–hcp transformation may be associated with the occurrence of a long-range interaction, corresponding to atomic interactions in 10 coordination spheres in the fcc lattice, and a many-body interaction responsible for the 4H-form stability.

We have studied the evolution of the defect structure and phase composition of low-carbon ferrite-perlite steel subjected to intense plastic deformation using diffraction electron microscopy. It has been shown that a high degree of deformation is accompanied by disruption of the perlite columns. We have found and described two perlite decay mechanisms: decay of the carbide plates by a path of their granulation due to dislocation slip and dissolution of cementite arising from the outflow of carbon atoms from the carbide phase into ferrite crystal lattice defects. We have described the phenomenon of morphological reconstruction of the cementite-phase particles (a transition from layers to spheres) under plastic deformation conditions.

The paper describes the results of mathematical modelling of diesel fuel catalytic dewaxing process, performed taking into account the factors of process nonstationarity driven by changes in process technological parameters, feedstock composition and catalyst deactivation. The error of hydrocarbon contents calculation via the use of the developed model does not exceed 1.6 wt.%. This makes it possible to apply the model for solution to optimization and forecasting problems occurred in catalytic systems under industrial conditions. It was shown through the model calculation that temperature in the dewaxing reactor without catalyst deactivation is lower by 19 °С than actual and catalyst deactivation degree accounts for 32 %.

Fragmentary substructure of 30CrMnSiA steel after rolling deformation has been studied. It was stated that in the material under test the volume share of anisotropic fragments makes 25% and isotropic — 75%. It was found out that martensite structure is completely broken in the rolling process.

In the work we studied the substructure of 30KhGSA steel after rolling. A relation has been established between the macrofracture of the specimen and its dislocation substructure. The formation and completion of a fragmented substructure with precipitation of carbides at the junctions of fragments during rolling indicate that the lifetime is close to exhaustion. Annealing that partially or completely destroys the fragmented substructure causes microcracks to collapse and heal, eliminates the microcrack nucleation sites, eliminates trajectories of facilitated microcrack growth, which follow subboundaries, and restores the plasticity of the steel.

Here we survey researches dealing with regularities and mechanisms for the bulk changes in properties in metals and alloys on surface treatment with low-energy plasmas. Descriptions are given of dislocations and dislocation-loop generation and of the formation of dislocation substructures. The dislocation density increases with irradiation time and as the distance from the surface decreases or as the yield point decreases. The effect is nonmonotonically dependent on the irradiation voltage and screening conditions. The types of dislocation structure formed are similar to those produced in plastic strain.

Substructural and phase transformations in the course of plastic deformation in tempered 34KhN3MFA steel are considered. A relation is established between the type of substructure and the phase state of carbon. A direct relation is established between the carbon content in the solid solution and the crystal-lattice distortion. The carbon concentration at dislocations and fragment boundaries is determined.

The method of electron microscopy is used to study the fine structure of martensitic steel 17Kh4N2M2VF when subjected to rapid thermocyclic tempering. It is found that substructural and phase transformations take place in martensite due to repeated rapid temperature changes within the range 20–700°C. The phase transformations involve the decomposition of cementite and residual austenite and the formation of special carbides. The substructural changes are connected with fragmentation of the material. The density of high-angle fragment boundaries increases near the specimen surface along with scalar and excess dislocation density. The phase structural transformations entail the formation of long-range stress fields, the local relaxation of which leads to the development of microcracks and fracture of the material.

The evolution of the defect and carbide subsystems has been studied during the plastic deformation of chromium nickel steel with the structure of tempered martensite. A correlation has been established between the substructural transformation and the change during plastic deformation. The nondislocation shear resistance has been estimated.

Investigation of the submicrostructure formed in the near surface layers of ion implanted polycrystalline Cu was carried out using transmission electron microscopy. Ni and Hf ions were implanted in the pulsed-periodical regime at an accelerating voltage of 40 kV. Irradiation doses were equal to 1 × 10 17 ion cm -2 for Hf and 2.0 × 10 17 and 4.6 × 10 17 ion cm -2 for Ni. It has bees established that a developed dislocation submicrostructure was formed in Cu under ion implantation. The near-surface layers with the induced submicrostructure exceeded 100 μm. The dislocation density in the indicated layer increases approximately 15–40 times as compared with that in the initial state for recrystallization Cu and 20%–30% for work-hardened Cu. With increase in ion flux from 0.09 × 10 14 to 0.35 × 10 14 ion cm -2 s -1 the maximum dislocation density increases; further ion flux does not result in the dislocation density growth. The change in the temperature of irradiated Cu (343–523 K) does not result in the change of a dislocation structure character in the target near-surface layer.

We consider the similarities and differences between the band substructure and the packet-martensite structure in Ni3Fe alloyed with 38KhN3MFA steel. The variation of their quantitative characteristics with strain and with initial polycrystal grain size is analyzed. The main factors governing the morphological features and the behavior of the considered structures are found to be the laws governing the evolution of the dislocation-disclination ensemble.

A layer-by-layer electron-microscope analysis has been made of the defect structure at different depths from an irradiation surface to establish the effect of a gas-discharge plasma on the metals Fe, Cu, and Mo and the alloy Ni3Fe. A long-range effect has been established, namely, an increase in the scalar density of dislocations to depths of about 10 mm. The dislocation density increases with irradiation time, with approach to the irradiated surface, and with decrease of the yield point of the irradiated material. This effect depends nonmonotonically on the discharge voltage and the conditions of shielding of the samples. The types of the dislocasubstructures that are formed are similar to those formed in the case of plastic deformations.

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.

The present work is an experimental verification of the fulfilment of the known relation τ=α ∁ β□. Monocrystals of f.c.c. alloys with different orientation and state of order and polycrystals with different grain size were investigated. The dislocation substructure study was fulfilled by the transmission electron microscopy method in a wide deformation interval even up to destruction. It is established that the condition of the indicated relation fulfilment is the preservation of dislocation substructure similarity in plastic deformation. The quantitative criterion of this similarity is the dislocation distribution character and moments of the distribution which describe dislocation density evolution during the deformation. The dislocation substructure similarity is not fulfilled, as a rule, if the deformation reaches great value and dislocation density is changed about 1.5–2 degrees and more. In this case the dependence τ (□) is more complicated than is predicted by the indicated relation.