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The deformation of polycrystal grains is hampered by the action of nearby grains. Their influence on structural changes under uniaxial compression has been studied using molecular dynamics simulations. [100] single crystals were studied as a characteristic orientation of growth grains. This orientation is most found in products obtained by electron-beam surfacing of aluminum bronze. The patterns of slip, twinning, and the formation of deformation domains are traced depending on the conditions for limiting the shear towards the lateral faces of the sample. Shown, that the shear limitation and the complication of the stress tensor contribute to the earlier development of twinning. [ABSTRACT FROM AUTHOR]

The structure of aluminum bronze after electron-beam surfacing is represented by coarse grains with different crystallographic orientations, elongated in the direction of the temperature gradient. An urgent task is to predict the behavior of this ensemble of grains under plastic deformation. The deformation of individual crystallites was studied by the molecular dynamics method. Structural changes depending on the crystallographic orientation and the ratio of the geometric parameters of the single crystals were studied. The development of the deformation relief and dislocation structure depends on the orientation of the slip directions in the slip plane relative to the sample ends, the lateral faces, and mutual arrangement if the systems are equally loaded. It determines the activity of systems in local regions of the sample and the probability of interaction of dislocations. The smallest dislocation interaction is observed for the 〈110〉 orientation. The general patterns of deformation relief formation obtained within the framework of computer simulation methods are consistent with the experimentally observed results. [ABSTRACT FROM AUTHOR]

The paper shows the regularities of plastic deformation and fragmentation of pure copper single-crystal after friction stir welding. The obtained data indicate a high role of deformation bands formation with changed orientation of crystal lattice along the contour of the stir zone. Near the stir zone, a larger number of deformation bands are also identified, in which fragmentation of the material into separate grains can already be detected. Near the stir zone, material fragmentation is characterized by the predominance of small-angle boundaries and smooth misorientations in the zone of thermomechanical influence, while in the mixing zone—by more angular boundaries. [ABSTRACT FROM AUTHOR]

The deformation mechanism of Hadfield steel depends on the crystallographic orientation and the sign of the load. Deformation occurs by slip and twinning, which affects the properties during nanoindentation. The paper studies the orientation dependence of the nanoindentation parameters of Hadfield steel. It is found that the nanohardness is the higher the larger the number of equally loaded slip systems. The difference in the elastic modulus depending on the crystallographic orientation can reach 50%. The highest hardness and elastic modulus are determined for the indented {001} plane. Compression deformation in this crystallographic direction gives rise to active twinning in Hadfield steel. [ABSTRACT FROM AUTHOR]

The authors of the article studied the deformation features of quartz (SiO2) and pyrite (FeS2) in the rocks of the Gabriel mine, earlier. The presence of water in quartz is confirmed in this work. In addition, the deformation features of plagioclase ((Ca, Na) [AlSi3O8]) and its chemical composition are studied. Fragile deformations in the region of double boundaries of plagioclase have not only a chemical composition, but also a tensor nature. [ABSTRACT FROM AUTHOR]

We studied the possibility to produce a high-performance metal matrix composite (MMC) based on aluminum bronze with reinforcing particles of boron carbide. MMC was manufactured by electron beam additive printing method using CuAl bronze wire and B4C powder. The hardness and structure of the produced material were studied. It was found that a strong gradient of the powder along the height of the MMC was formed in the printed material. The formation of this gradient results in an uneven increase in hardness in the composite layer of the sample. [ABSTRACT FROM AUTHOR]

Orientation dependence of deformation band pattern formed on the Cu-1.5Co-3Al single crystal faces during friction sliding in two different non-lubricated sliding regimes against a clean alumina surface and with transferred metal layer was studied. The deformation bands on the crystal faces were arranged in different formations such as rectilinear bands, crossing bands and band mesopacks. The crystallographic orientation of the normal load force and friction force determines the type of a deformation relief formed. The single crystal orientations with respect to normal load axis were [110] and on [110] and [1̅11] samples the preferential slipping by one of the equi-loaded slip planes was observed. [ABSTRACT FROM AUTHOR]

Rocks of the Gabriel mine (East Kazakhstan) belong to intensively modified milonites. These rocks in the Ore Altai are often ore-bearing for metals such as zinc, lead, copper and gold. Milonites are formed by imposing deformations on the original rocks. These rocks are interesting for large studies. Using the EBSD method allows us to investigate the deformation stage of mineral formation more detailed. In this work, we studied sections of quartz porphyroblasts with different volume fractions of pyrite. As a result, we determined the influence of the pyrite volume fraction on the degree of quartz deformation and the possible presence of water in the later stages of mineral. [ABSTRACT FROM AUTHOR]

Alteration in the deformation structure of copper single crystals and the Hadfield steel polycrystalline in the cross section depend on the distance from the friction surface. The following sequence of substructure formation has been determined: a mixing zone with nanograins and nanotwins, a fragmented substructure with microbands, microtwins, a cellular and tangled substructures, and a substructure with chaotic dislocation distribution. Hadfield steel has a much greater number of nanotwins in the surface layer than copper and it has a layer of microtwins. Evolution of dislocation structure when approaching the friction area was found to be similar to the evolution of substructures under active plastic deformation. [ABSTRACT FROM AUTHOR]

The development of deformation relief on the surface of Hadfield steel single crystals is investigated using the method of scratching with a linearly increasing load. The orientation of the indenter motion and the direction of the normal load in the directions correspond to the angles of the standard stereographic triangle allow characterization of the crystallography of slip. The complex nature of the stress field near the surface of the indenter activates the maximum number of possible slip planes for each crystallographic orientation. This stress field determines the shear areas of the specific plane. [ABSTRACT FROM AUTHOR]

Abrasive wear is not favorable for Hadfield steel. The connection between the acoustic emission signal and the formation of microcracks in the case of abrasive wear is evaluated during scratch tests. The amplitude increase of the acoustic emission signal coincides with the formation of microcracks on the scratch surface in most cases. The acoustic emission signal amplitude is greater the longer the crack length and the number of cracks. The direction of the indenter motion has a greater influence on crack formation than the plane of scratch testing. [ABSTRACT FROM AUTHOR]

The aim of this work is to evaluate the influence of the crystallographic orientation and crystal’s symmetry on the ability to self-organize under a compression deformation at various scale levels. Nickel single crystals with the [111] contraction axis and {110}, {112} lateral faces were investigated. Single crystals in the shape of rectangular and triangular prisms were used in this work. Different geometric shapes of the crystals made it possible to establish the influence of the symmetry crystal on the plastic deformation processes. The methods of fractal analysis were used to assess the self-organization level. It is established that the processes of self-consistency of deformation at the microlevel are realized due to the self-organization of the dislocation structure, at the mesolevel due to a correlated shear in parallel slip planes. It is shown that the coincidence of the sample symmetry with the crystallographic symmetry of the compression axis promotes an increase in the degree of the crystal deformation self-consistency at all scale levels. [ABSTRACT FROM AUTHOR]

Friction is a complex dynamic process. Direct observation of processes occurring in the friction zone is impossible due to a small size of a real contact area and, as a consequence, requires various additional methods applicable to monitor a tribological contact state. One of such methods consists in the analysis of acoustic emission data of a tribological contact. The use of acoustic emission entails the problem of interpreting physical sources of signals. In this paper, we analyze the evolution of acoustic emission signal frames in friction of Hadfield steel single crystals. The chosen crystallographic orientation of single crystals enables to identify four stages related to friction development as well as acoustic emission signals inherent in these stages. Acoustic emission signal parameters are studied in more detail by the short-time Fourier transform used to determine the time variation of the median frequency and its power spectrum. The results obtained will facilitate the development of a more precise method to monitor the tribological contact based on the acoustic emission method. [ABSTRACT FROM AUTHOR]

We analyze the misorientation of [111] FCC single crystals during compression deformation. The development of local areas of misorientation is considered at different scale levels (starting with the macrolevel (specimen surface) and ending with a dislocation structure). It is shown that the accumulation of misorientation at dislocation subsystems contributes to the misorientation accumulation at higher scale levels. [ABSTRACT FROM AUTHOR]

The paper is devoted to deformation relief formed on the surface of Hadfield steel while scratching under a linearly increasing load. The deformation relief is analyzed to detect regions with microfracture of the surface layer of Hadfield steel. Crack generation regions coincide with regions of the most intense acoustic emission (AE) signal. Single and multiple slip bands are observed in various grains of the material. As the load increases, slip bands thicken and grains with multiple slip are more frequent. [ABSTRACT FROM AUTHOR]

The paper deals with the evolution of the deformation relief formed on lateral faces of single crystals of Hadfield steel during dry sliding friction. The use of single crystals with the predetermined orientation enables to analyze the development of shear systems subject to the duration of tribological tests. As the test duration increases, slip bands are curved and thicken in the near-surface region. After 24 hours of friction, single crystals of Hadfield steel demonstrate the maximum hardening. Afterwards, the wear process begins, which is followed by the repeated strain hardening of the specimens. After 48 hours of friction, the height of the deformation relief nearly halves on all of the three faces, as compared to that observed after 24 hours of friction. Differences in the propagation height of slip bands on the faces occur due to the uneven running-in as well as the complex involvement pattern of shear systems into the deformation process. [ABSTRACT FROM AUTHOR]

Compression strain-induced surface pattern on copper single crystal faces was studied by means of optical, confocal laser and scanning electron microscopies. It was shown that apart from work-hardening effect of previously formed deformation macrobands there is a pure geometrical (size) effect which serves for changing the conditions for further deformation within the deformation macroband zones by folded structure formation. [ABSTRACT FROM AUTHOR]

This work presents the experimental results concerning the research of the morphology of the face-centered cubic single crystal surface after compression deformation. Our aim is to identify the method of forming a quasiperiodic profile of single crystals with different crystal geometrical orientation and quantitative description of deformation structures. A set of modern methods such as optical and confocal microscopy is applied to determine the morphology of surface parameters. The results show that octahedral slip is an integral part of the formation of the quasiperiodic profile surface starting with initial strain. The similarity of the formation process of the surface profile at different scale levels is given. The size of consistent deformation regions is found. This is 45 µm for slip lines ([001]-single crystal) and 30 µm for mesobands ([110]-single crystal). The possibility of using two- and three-dimensional roughness parameters to describe the deformation structures was shown. [ABSTRACT FROM AUTHOR]

A relationship between different-scale deformations of crystals has not been established yet. In order to solve this task, we investigate the development of a deformation relief and dislocation structure in nickel single crystals after deformation. The stress tensor, crystallography, and geometry of specimens affect the organization of some shear along corresponding systems of sliding. The organization of shear shows some features of self-organization. It is associated with the self-organization in the dislocation subsystem analyzed previously. The effectiveness of reducing external and internal stresses determines patterns of deformation processes at different scale levels. [ABSTRACT FROM AUTHOR]

The authors analyze folding in concavity areas. Special aspects of folding are determined both for natural concavities stipulated by specifics of crystallographic orientation and for deliberately created concavities inside a U-shaped cut. It is shown that at the macrolevel folding is caused by concavity areas, in other words the stress condition pattern has primary influence on initiation of folds. Development of folding structures is followed by misorientation of local areas inside the crystal. The misorientation leads to an increase in the Schmidt factor and initiating additional slide patterns inside the crystal at the mesolevel. Development and accumulation of misorientations at the microlevel correlate with those in the dislocation structure. A U-shaped incision helps to activate a larger number of slip systems and the emergence of additional deformation domains. [ABSTRACT FROM AUTHOR]

The paper presents the research of the weld structure of two Ti specimens of the type VT6 that have nano- and submicrocrystalline structures. Electrical contact welding is used to obtain welds. The acicular structure is formed in the weld area. Two types of defects are detected, namely micropores and microcracks. [ABSTRACT FROM AUTHOR]

This paper studies the results of electron backscatter diffraction analysis of naturally deformed polycrystalline olivine. It also defines the dependence of lattice-preferred orientations of grains on their microstructural position and size. The authors detect the basic mechanisms' consequence and thermal dynamic modes of deformation. They also show that the development of a polycrystalline structure is determined by the following consecutive activation of sliding systems (010)[100] -> {0kl}[100] -> (100)[010] -> {100}[001] -> {110}[001]' when dislocation sliding and diffusion creep change under the temperature decrease from 1000°C to 650°C. [ABSTRACT FROM AUTHOR]