The effect of uniaxial tensile stress on the atomic structure and relief of the subsurface layer of molybdenum ribbons has been studied. The destruction of the Mo (100) face with the formation of crystallites was revealed near mouth of the crack. At the same time, the block structures are found to rotate both in the lateral plane and in its perpendicular plane. The surface layer structure in the lateral plane of the ribbon is fragmented into sections, which is associated with the surface relief at different scales. With a help of the concept of multifractal formalism, the spectra of singularities of the initial, loaded and ruptured surface are calculated. It is found that the width of the singularity spectrum, can serve as an indication of the forthcoming rupture.

The effect of uniaxial tensile stress on the atomic structure and relief of the subsurface layer of molybdenum ribbons has been studied. The destruction of the Mo (100) face with the formation of crystallites was revealed near the crack tip. At the same time, the block structures are found to rotate both in the lateral plane and in its perpendicular plane. The surface layer structure in the lateral plane of the ribbon is fragmented into sections, which is associated with the surface relief at different scales. With a help of the concept of multifractal formalism, the spectra of singularities of the initial, loaded and ruptured surface are calculated. It is found that the width of the singularity spectrum, can serve as an indication of the forthcoming rupture.. Keywords: molybdenum ribbon, mechanical load, annealing, destruction of material, block structures, surface, multifractal formalism.

In this paper, we study changes in the near-surface layers of corrugated Pt foils that are considered as multiscale diffraction gratings in the uniaxial tension process. The structure transformation and the ordering degree are analyzed at various stages of loading the samples up to their destruction. Using the concept of multifractal formalism, a criterion for the efficiency of using these foils is proposed.

Исследованы изменения приповерхностных слоев гофрированных Pt-фольг, рассматриваемых в качестве мультимасштабных дифракционных решеток в процессе одноосного растяжения. Произведен анализ трансформации структуры и степени упорядоченности на разных этапах нагружения образцов, вплоть до их разрушения. С помощью концепции мультифрактального формализма предложен критерий эффективности использования данных фольг. Ключевые слова: гофрированная фольга, дифракционная решетка.

In this paper we investigated the crystallization of NiTi metallic glass foils of equiatomic composition by XRD and AFM. The initial foil surface which was obtained by the melt spinning method contained only cristalline phases of impurities. Ten-minute annealing at 500°C leads to phase transition in the form of devitrification of Ni50Ti50 phase. The analisys of foil surface geometry included calculation of direct inhomogeneities characteristics, roughness and fractal dimension, as well as the parameters of multifractal fromalism. It was showen that after ten-minute heat treatment at 500°C all above mentioned characteristics have local extrema. In particular there is a minimum of the widths of the singularities spectra which indicates the monofractalization of the system.

Morphology dynamics of recrystallized tungsten foil surface under uniaxial stretching was investigated in situ by LEED, Auger, AFM, SEM an X-Ray fluorescent analysis. It has been found that before the rupture of the sample the transition from multifractality to monofractality occurs in a few stages: narrowing of the width of multifractal singularity spectrum of surface defects, turn of structural blocks of dominating face W (112) and transition of the lattice of dominating face into diffractive disordered state.

The dynamics of changes in the surface morphology of recrystallized tungsten foil under the action of uniaxial tension was studied in situ by the methods of low-energy electron diffraction, electron Auger spectroscopy, atomic force microscopy, scanning electron microscopy, and energy dispersive scattering. It was established that, before the rupture of the sample, the multifractality–monofractality transition consists of several stages: the narrowing of the multifractal spectra of the singularities of the surface, the rotation of the structural blocks of the dominant (112) tungsten face, and the transition of the lattice of the dominant face into a diffractive-disordered state.

Crystallization of NiTi ribbon metallic glass of equiatomic composition has been studied by x-ray structural analysis and atomic force microscopy. The surface of the original ribbon obtained by spinning contained only crystallites of impurity phases. As a result of exposure to annealing for 10 min at a temperature of 500°C, a phase transition has been observed in the form of Ni 50 Ti 50 phase ordering. The parameters of inhomogeneities, roughness, fractal dimension, and values of multifractal formalism have been calculated in the analysis of the ribbon surface geometry. It has been found that all the above characteristics had local extremes after heat treatment at 500°C for 10 min. In particular, the minimum of the values of the widths of the spectra of singularities has been observed, indicating system monofractalization.

The micro- and nanoreliefs of the loaded surfaces of a Fe77Ni1Si9B13 metal glass are probed via scanning tunneling and atomic force microscopies, scanning electron microscopy, and X-ray fluorescence. The fractal characteristics of surfaces are evaluated via the multifractal approach. As found, the variations in a singularity spectrum width, calculated from the tunneling and atomic force microscopies, may be useful for predicting the forthcoming fracture. An increase in the breaking strength of ribbons subjected to hydrostatic compression is due to decreasing microporosity of a near-surface layer, which corresponds to the surface smoothing.

AbstractThe micro- and nanoreliefs of the loaded surfaces of a Fe_77Ni_1Si_9B_13 metal glass are probed via scanning tunneling and atomic force microscopies, scanning electron microscopy, and X-ray fluorescence. The fractal characteristics of surfaces are evaluated via the multifractal approach. As found, the variations in a singularity spectrum width, calculated from the tunneling and atomic force microscopies, may be useful for predicting the forthcoming fracture. An increase in the breaking strength of ribbons subjected to hydrostatic compression is due to decreasing microporosity of a near-surface layer, which corresponds to the surface smoothing.

We investigated the formation of nanostructures on the surface of rolled thin platinum foils at the heating and "tension-compression" cycles in ultrahigh vacuum. The surface was characterized by LEED, AES, AFM, optical microscopy and micro Raman spectroscopy (MRS). Quantitative characterization of the surface relief was made by fractal analysis. About 95 % of the Pt foil surface was made by close packed Pt (111) face with unidirectional rippled multi-scale relief. Under the applied tension, changes in the LEED and AFM patterns were observed and it was found that, preceding the formation of the main crack, the surface becomes difractionally disordered with relief fractality turning to an isotropic one. Moreover, at the foil surface, near the clips of the sample holder (about 5 % of the surface area), the surface groups of micro crystals with sizes about 10 mu m were observed which were identified by MRS as microdiamonds and diamond-like carbon.

A change in the surface morphology of recrystallized tungsten foil under the effect of uniaxial tension in ultrahigh vacuum is studied by low-energy electron diffraction and atomic force microscopy. It is found by using low-energy electron diffraction that on the foil surface consisting of separate blocks with dominant face (112), there is a turn in orientation of the structural blocks. The analysis of the topograms of different areas of the side surface of a broken sample, obtained by atomic force microscopy, enabled the association of changes in the atomic structure of the surface layers of foil with a change in its relief by mechanical action.

Методами дифракции медленных электронов и атомной силовой микроскопии исследовалось изменение морфологии поверхности рекристаллизованной фольги W под воздействием одноосного растяжения в сверхвысоком вакууме. С помощью дифракции медленных электронов установлено, что под влиянием одноосного растяжения на поверхности фольги, состоящей из отдельных блоков доминирующей грани (112), происходит разворот структурных блоков. Анализ топограмм различных областей боковой поверхности разорванного образца, полученных методом атомной силовой микроскопии, позволил связать изменения атомной структуры поверхностных слоев фольги с изменением ее рельефа при механическом воздействии. DOI: 10.21883/FTT.2017.02.44053.269

Thin platinum foils and ribbons of the amorphous alloy Fe 77 Ni 1 Si 9 B 13 with fractal surfaces made of unidirectional multiscale surface ripples have been prepared. The surface relief and atomic structure of these foils have been investigated by low-energy electron diffraction, atomic force microscopy, and scanning tunnelling microscopy. It has been shown that Pt foils with a fractal surface relief have the prospect for application as reflective diffraction gratings. A model has been proposed and used to calculate the light scattering on unidirectional rippled surface structures of Pt foils.

Thin platinum foils and metallic glass ribbons with a fractal surface consisting of different-scale unidirectionally oriented ripples have been fabricated using special thermoplastic processing. The general fractal dimension of the rippled surface and dimensions along and across the ripples have been measured. The optical spectra of a PRK-4 lamp using rippled Pt(111) foils as reflective diffraction gratings have been determined. A model describing the mechanism of the formation of surface unidirectional fractal structures during deformation has been proposed.

Changes in the atomic structure and surface morphology of a recrystallized molybdenum foil under the action of uniaxial tension in ultrahigh vacuum have been studied by low -energy electron diffraction (LEED) and atomic-force microscopy (AFM). It is established that uniaxial tension of the foil surface, which consists of separate blocks of dominating (100) face with 1 × 1 structure, leads to a local destruction of this face and the rotation of blocks. AFM topographs of various regions on the surface of fractured samples have been obtained. The variation of the LEED patterns agrees well with the evolution of the surface relief measured by AFM.

The atomic structure and surface relief of thin cold-rolled platinum foils upon recrystallization annealing and loading under ultrahigh vacuum conditions have been studied by low energy electron diffraction (LEED), atomic force microscopy (AFM), and scanning tunneling microscopy (STM). The surface of samples upon high-temperature annealing and subsequent uniaxial extension of recrystallized Pt foils represents a fractal structure of unidirectional ripples on various spatial scales. The total fractal dimension of this surface is D GW = 2.3, while the fractal dimensions along and across ripples are D ‖ ≈ 1 and D ⊥ ≈ 1.3, respectively. The optical spectra of a halogen lamp and a PRK-2 mercury lamp were recorded using these rippled Pt foils as reflection diffraction gratings. It is shown that Pt foils with this surface relief can be used as reflection diffraction gratings for electromagnetic radiation in a broad spectral range.

The Raman spectra of single crystalline RE (rare earth) tetraborides REB4 (RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu) are measured and analysed with respect to the dependence of the phonon frequencies on the rare earth metal. Phonons representing octahedral B6 units are identified by comparison to the according phonon modes of hexaborides. Their relative force parameters are estimated.

The atomic structure and surface relief of a polycrystalline platinum foil upon rolling and subsequent recrystallization in ultrahigh vacuum have been studied by low energy electron diffraction (LEED) and atomic force microscopy (AFM). The symmetry of LEED patterns shows that the surface structure of recrystallized platinum foil corresponds to (111) face, but different shapes of diffraction maxima are indicative of a diversity of the geometric relief. AFM data reveal various types of the surface relief, including flat, rippled in one direction, and differently oriented, which are considered in comparison to the corresponding LEED patterns. Using the established laws, it is possible to trace the formation of various reliefs by diffraction techniques without using probe methods.

The micro- and nanoreliefs of loaded lateral surfaces and fracture surfaces of foils of the Fe 77 Ni 1 Si 9 B 13 , Fe 58 Ni 20 Si 9 B 13 , and Fe 70 Cr 15 B 15 amorphous alloys have been investigated using scanning tunneling and atomic force microscopy. The isotropic and anisotropic surface reliefs have been examined. The fractal dimensions of the surfaces of loaded specimens and the fracture surfaces along and across the direction of crack propagation have been estimated using the box counting method. Fractal characteristics of the surfaces, such as the Hölder exponent and the half-width of the singularity spectrum, have been calculated using the wavelet transform method. It has been found that, on the topographies with a clearly pronounced anisotropy of the relief, the surface is fractal in only one direction, and the surface is fractal in two directions on the topographies with a less pronounced anisotropy of the relief. The fractal characteristics of the lateral surfaces and the fracture surfaces with allowance made for their anisotropy have close values. It has been shown that the formation of two types of fracture surfaces is adequately described in terms of the model of a cellular automaton.