Yuri Abzaev - Academia.edu (original) (raw)

Papers by Yuri Abzaev

Research paper thumbnail of Study of deformations evolution in near-surface layers of adhesive joints

Nucleation and Atmospheric Aerosols, 2017

Research paper thumbnail of Experimental study of deformation fields under axial tension on composite surface with prestressed carbon tape

Nucleation and Atmospheric Aerosols, 2022

Research paper thumbnail of Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

Nanomaterials, Jan 11, 2018

Research paper thumbnail of Features of the structural phase state of a weld produced by electron-beam welding in the submicrocrystalline grade 2 titanium alloy

MATEC web of conferences, 2018

This paper presents the results of structural studies for a welded joint of the Grade 2 titanium ... more This paper presents the results of structural studies for a welded joint of the Grade 2 titanium alloy in submicrocrystalline and microcrystalline states produced by electron beam welding when joining 2mm-thick plates. Microhardness distribution patterns of the Grade-2 titanium alloy in micro-and submicrocrystalline states are identified in the weld zone and heat-affected zone. These patterns reflect a difference in structural phase states. It is assumed that one of the key factors affecting both the structural state and microhardness distribution in the weld zone and heat-affected zone during electron-beam welding is high concentration of oxygen atoms embedded into the crystal lattice of -Ti-based solid solution.

Research paper thumbnail of High-temperature structure formation in cement depending on curing time

Nucleation and Atmospheric Aerosols, 2017

The paper presents a comprehensive study of the quantitative phase composition of Portland cement... more The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement shows that the bulk structures of clinker phases are not involved in the process of hydration. Experiments demonstrate that the crystal lattices of these phases are highly stable, and their binding energy tends to increase with the rise in curing time. The atomic-binding energy in crystal lattices of alite and larnite ranges within (187.379…187.616) and (496.764…497.016) eV, respectively. A high level of the atomic-binding energy indicates to the dissolution occurring at the interface between the solid and liquid phases. A certain atomic re-arrangement inside the crystal lattices can be accepted within the interval of stability as well as a variation of the number of atoms in unit cells.The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement sho...

Research paper thumbnail of Aluminum Alloying Effect on Porous Nitinol Properties Obtained by Self-Propagating High-Temperature Synthesis

Social Science Research Network, 2021

Research paper thumbnail of Thermodynamic simulation of Portland cement hydration with different water content

PHYSICAL MESOMECHANICS OF CONDENSED MATTER: Physical Principles of Multiscale Structure Formation and the Mechanisms of Nonlinear Behavior: MESO2022

Research paper thumbnail of Influence of Dy and Ho on the Phase Composition of the Ti-Al System Obtained by ‘Hydride Technology’

Materials

The manuscript describes the phase composition, microstructure, some physical and mechanical prop... more The manuscript describes the phase composition, microstructure, some physical and mechanical properties of the Ti-Al system with addition of 2 at. % Dy (TAD) and Ho (TAH) obtained by “hydride technology”. Phase diagrams for Ti-Al-Dy and Ti-Al-Ho at a temperature of 1150 °C and basic properties for ternary phases Dy₆Ti₄Al₄₃ and Ho₆Ti₄Al₄₃ were calculated. A crystallographic database of stable and quasistable structures of the known elemental composition was created in the USPEX-SIESTA software by means of an evolutionary code. The calculations show that adding REM leads to a significant stabilizing effect in each Ti-Al-Me (Me = Dy, Ho) system without exception. It has been established that the lattice energies of AlTi3Ho and AlTi3Dy are, respectively, equal to: EAl4Ti12Dy3 = −32,877.825 eV and EAl4Ti12Dy3 = −31,227.561 eV. In the synthesized Ti49Al49Ho2 compound, the main phases include Al-Ti, Al3Ti3 and Al4Ti12Ho3 and the contributions to the theoretical intensity are equal to 44.83...

Research paper thumbnail of The Influence of Scandium on the Composition and Structure of the Ti-Al Alloy Obtained by “Hydride Technology”

Nanomaterials

In this study the influence of scandium on the structural and phase state of the Ti-Al alloy obta... more In this study the influence of scandium on the structural and phase state of the Ti-Al alloy obtained by the method of “Hydride Technology” (HT). The Rietveld method has allowed for determining the content of basic phases of the 49at.%Ti-49at.%Al-2at.%Sc system. By means of the methods of transmission electron microscopy (TEM) and X-ray spectral microanalysis, it has been established that scandium additives into the Ti-Al system result in the change of the quantitative content of phases in local regions of the structure. The Ti2Al5 phase has been found, and Ti2Al has been absent. In the morphology of substructures Ti-Al and Ti-Al-Sc there are lamellar structures or lamellae; the peculiarities of the distribution, fraction and size of which are influenced by scandium additives. The average width of Al-rich lamellae has been 0.85 µm, which is four times greater than that for the Ti-Al system (0.21 µm). For Ti-rich lamellae of the sample of the Ti-Al-Sc alloy, the average width of the ...

Research paper thumbnail of Experimental study of deformation fields under axial tension on composite surface with prestressed carbon tape

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE “PHYSICAL MESOMECHANICS. MATERIALS WITH MULTILEVEL HIERARCHICAL STRUCTURE AND INTELLIGENT MANUFACTURING TECHNOLOGY”

The features of evolution in space and time of distributions of deformation fields on the surface... more The features of evolution in space and time of distributions of deformation fields on the surface of the composite, reinforced with carbon tape, have been studied at meso-and macroscopic scale levels by method of correlation of digital images. The obtained pictures reflect in detail the evolution of distribution of isofields of relative deformations on the surface of composite, corresponding to different degrees of deformation action under uniaxial tension. Based on the results of the conducted studies of the carbon composite samples, numerical values of the strain concentration factor, expressing the ratio of the maximum value of deformations on the surface of the sample to the total average deformation over the entire working field of the sample, have been obtained to estimate the concentration of deformations. It has been established that the strain concentration factor is equal to 1.3 for the non-stressed carbon composite of carbon plastic tapes and 1.21 for the prestressed one. Modification of the carbon composite during prestress molding leads to a 22% reduction in stress concentration on the surface of the carbon composite, increases strength by 37.8%, deformation by 25% and modulus of elasticity by 10.25%.

Research paper thumbnail of Study of macroplastic flow in surface layers of porous titanium nickelide by digital image correlation

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE “PHYSICAL MESOMECHANICS. MATERIALS WITH MULTILEVEL HIERARCHICAL STRUCTURE AND INTELLIGENT MANUFACTURING TECHNOLOGY”

The work presents a study the mechanical properties of porous titanium nickelide and to study the... more The work presents a study the mechanical properties of porous titanium nickelide and to study the evolution of deformation fields at the meso-and macroscopic level on the surface of porous titanium nickelide samples of different thicknesses by the method of correlation of digital images under uniaxial tension. Optical system Vic-3D allows to reveal the peculiarities of evolution in space and time of distributions of deformation fields. With a decrease in the thickness of the samples and with their tension from the averaged deformation over the working field of the sample by more than 0.005%, this leads to an enlargement of the characteristic size of local deformation regions in speckle patterns on the surface of the 3D framework of the porous material. Based on the analysis of the deformation curves two stages of deformation are distinguished. It was found that the values of the deformation hardening coefficient n depend on the sample thickness.

Research paper thumbnail of Aluminum Alloying Effect on Porous Nitinol Properties Obtained by Self-Propagating High-Temperature Synthesis

SSRN Electronic Journal, 2021

Research paper thumbnail of Features of the structural phase state of a weld produced by electron-beam welding in the submicrocrystalline grade 2 titanium alloy

MATEC Web of Conferences, 2018

This paper presents the results of structural studies for a welded joint of the Grade 2 titanium ... more This paper presents the results of structural studies for a welded joint of the Grade 2 titanium alloy in submicrocrystalline and microcrystalline states produced by electron beam welding when joining 2-mm-thick plates. Microhardness distribution patterns of the Grade-2 titanium alloy in micro- and submicrocrystalline states are identified in the weld zone and heat-affected zone. These patterns reflect a difference in structural phase states. It is assumed that one of the key factors affecting both the structural state and microhardness distribution in the weld zone and heat-affected zone during electron-beam welding is high concentration of oxygen atoms embedded into the crystal lattice of α–Ti-based solid solution.

Research paper thumbnail of Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

Nanomaterials, 2018

The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium c... more The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation.

Research paper thumbnail of High-temperature structure formation in cement depending on curing time

AIP Conference Proceedings, 2017

The paper presents a comprehensive study of the quantitative phase composition of Portland cement... more The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement shows that the bulk structures of clinker phases are not involved in the process of hydration. Experiments demonstrate that the crystal lattices of these phases are highly stable, and their binding energy tends to increase with the rise in curing time. The atomic-binding energy in crystal lattices of alite and larnite ranges within (187.379…187.616) and (496.764…497.016) eV, respectively. A high level of the atomic-binding energy indicates to the dissolution occurring at the interface between the solid and liquid phases. A certain atomic re-arrangement inside the crystal lattices can be accepted within the interval of stability as well as a variation of the number of atoms in unit cells.The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement sho...

Research paper thumbnail of Study of deformations evolution in near-surface layers of adhesive joints

This paper presents the study of the evolution in situ of distribution of local deformations in n... more This paper presents the study of the evolution in situ of distribution of local deformations in near-surface layers in pads made of carbon lamellas under strain deformation. The specimens were produced from two face-to-face docked steel pads 120×40×4 mm and two carbon lamellas FibARM Lamel 120×40×1,2 mm joint using the adhesion 'FibARM Resin Laminate+". The strain tests were performed using the "INSTRON 3386" test bed with a maximum tension of 100 кN (10,19 тs). Optical measurement system VIC-3D was used to identify the evolution of deformations distribution in the near-surface layers. The VIC-3D system allowed obtaining the images that reflect the evolution of distribution of relative deformations iso-fields under different loads. In situ experimental research was conducted focused on strain deformations in specimens made of a layered composite: metal/adhesive/carbon lamella. A crack in the specimen was modeled, which allowed determining that with a growth of the overall deformation there develops an evolution of special structural elements from chaotic (along the whole lamella area) to localized ones with higher deformation values in the crack region. It was established that at higher levels of overall deformation in the crack region on the carbon lamella surface, the maximum deformation region with one extremum is divided by a narrow line of low deformation into two parts along the joint of steel plates. A limit deformation is identified.

Research paper thumbnail of The Structural and Phase State of the TiAl System Alloyed with Rare-Earth Metals of the Controlled Composition Synthesized by the “Hydride Technology”

Metals, 2020

The structural state and the quantitative phase analysis of the TiAl system, alloyed with rare-ea... more The structural state and the quantitative phase analysis of the TiAl system, alloyed with rare-earth metals synthesized using hydride technology, were studied in this work. Using the Rietveld method, the content of the major phases in the initial system Ti(50 at.%)–Al(50 at.%), as well as Ti(49 at.%)–Al(49 at.%), with alloying additions Ta, Y and Dy having a high accuracy was determined. The methods of scanning electron microscopy, transmission electron microscope and X-ray spectral microanalysis of the local areas of the structure for studying the distribution of alloying elements were used. The energies of lattices of separate phases were also determined after the full-profile specification. All the lattices of the identified structures (about 30) turned out to be stable. It was established that in the Ti(49 at.%)–Al(49 at.%) systems under study with alloying additions of metals Ta, Y and Dy, there were intermetallides composed of AlTi3, TiAl in the hexagonal, tetragonal and tricl...

Research paper thumbnail of Study of deformations evolution in near-surface layers of adhesive joints

Nucleation and Atmospheric Aerosols, 2017

Research paper thumbnail of Experimental study of deformation fields under axial tension on composite surface with prestressed carbon tape

Nucleation and Atmospheric Aerosols, 2022

Research paper thumbnail of Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

Nanomaterials, Jan 11, 2018

Research paper thumbnail of Features of the structural phase state of a weld produced by electron-beam welding in the submicrocrystalline grade 2 titanium alloy

MATEC web of conferences, 2018

This paper presents the results of structural studies for a welded joint of the Grade 2 titanium ... more This paper presents the results of structural studies for a welded joint of the Grade 2 titanium alloy in submicrocrystalline and microcrystalline states produced by electron beam welding when joining 2mm-thick plates. Microhardness distribution patterns of the Grade-2 titanium alloy in micro-and submicrocrystalline states are identified in the weld zone and heat-affected zone. These patterns reflect a difference in structural phase states. It is assumed that one of the key factors affecting both the structural state and microhardness distribution in the weld zone and heat-affected zone during electron-beam welding is high concentration of oxygen atoms embedded into the crystal lattice of -Ti-based solid solution.

Research paper thumbnail of High-temperature structure formation in cement depending on curing time

Nucleation and Atmospheric Aerosols, 2017

The paper presents a comprehensive study of the quantitative phase composition of Portland cement... more The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement shows that the bulk structures of clinker phases are not involved in the process of hydration. Experiments demonstrate that the crystal lattices of these phases are highly stable, and their binding energy tends to increase with the rise in curing time. The atomic-binding energy in crystal lattices of alite and larnite ranges within (187.379…187.616) and (496.764…497.016) eV, respectively. A high level of the atomic-binding energy indicates to the dissolution occurring at the interface between the solid and liquid phases. A certain atomic re-arrangement inside the crystal lattices can be accepted within the interval of stability as well as a variation of the number of atoms in unit cells.The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement sho...

Research paper thumbnail of Aluminum Alloying Effect on Porous Nitinol Properties Obtained by Self-Propagating High-Temperature Synthesis

Social Science Research Network, 2021

Research paper thumbnail of Thermodynamic simulation of Portland cement hydration with different water content

PHYSICAL MESOMECHANICS OF CONDENSED MATTER: Physical Principles of Multiscale Structure Formation and the Mechanisms of Nonlinear Behavior: MESO2022

Research paper thumbnail of Influence of Dy and Ho on the Phase Composition of the Ti-Al System Obtained by ‘Hydride Technology’

Materials

The manuscript describes the phase composition, microstructure, some physical and mechanical prop... more The manuscript describes the phase composition, microstructure, some physical and mechanical properties of the Ti-Al system with addition of 2 at. % Dy (TAD) and Ho (TAH) obtained by “hydride technology”. Phase diagrams for Ti-Al-Dy and Ti-Al-Ho at a temperature of 1150 °C and basic properties for ternary phases Dy₆Ti₄Al₄₃ and Ho₆Ti₄Al₄₃ were calculated. A crystallographic database of stable and quasistable structures of the known elemental composition was created in the USPEX-SIESTA software by means of an evolutionary code. The calculations show that adding REM leads to a significant stabilizing effect in each Ti-Al-Me (Me = Dy, Ho) system without exception. It has been established that the lattice energies of AlTi3Ho and AlTi3Dy are, respectively, equal to: EAl4Ti12Dy3 = −32,877.825 eV and EAl4Ti12Dy3 = −31,227.561 eV. In the synthesized Ti49Al49Ho2 compound, the main phases include Al-Ti, Al3Ti3 and Al4Ti12Ho3 and the contributions to the theoretical intensity are equal to 44.83...

Research paper thumbnail of The Influence of Scandium on the Composition and Structure of the Ti-Al Alloy Obtained by “Hydride Technology”

Nanomaterials

In this study the influence of scandium on the structural and phase state of the Ti-Al alloy obta... more In this study the influence of scandium on the structural and phase state of the Ti-Al alloy obtained by the method of “Hydride Technology” (HT). The Rietveld method has allowed for determining the content of basic phases of the 49at.%Ti-49at.%Al-2at.%Sc system. By means of the methods of transmission electron microscopy (TEM) and X-ray spectral microanalysis, it has been established that scandium additives into the Ti-Al system result in the change of the quantitative content of phases in local regions of the structure. The Ti2Al5 phase has been found, and Ti2Al has been absent. In the morphology of substructures Ti-Al and Ti-Al-Sc there are lamellar structures or lamellae; the peculiarities of the distribution, fraction and size of which are influenced by scandium additives. The average width of Al-rich lamellae has been 0.85 µm, which is four times greater than that for the Ti-Al system (0.21 µm). For Ti-rich lamellae of the sample of the Ti-Al-Sc alloy, the average width of the ...

Research paper thumbnail of Experimental study of deformation fields under axial tension on composite surface with prestressed carbon tape

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE “PHYSICAL MESOMECHANICS. MATERIALS WITH MULTILEVEL HIERARCHICAL STRUCTURE AND INTELLIGENT MANUFACTURING TECHNOLOGY”

The features of evolution in space and time of distributions of deformation fields on the surface... more The features of evolution in space and time of distributions of deformation fields on the surface of the composite, reinforced with carbon tape, have been studied at meso-and macroscopic scale levels by method of correlation of digital images. The obtained pictures reflect in detail the evolution of distribution of isofields of relative deformations on the surface of composite, corresponding to different degrees of deformation action under uniaxial tension. Based on the results of the conducted studies of the carbon composite samples, numerical values of the strain concentration factor, expressing the ratio of the maximum value of deformations on the surface of the sample to the total average deformation over the entire working field of the sample, have been obtained to estimate the concentration of deformations. It has been established that the strain concentration factor is equal to 1.3 for the non-stressed carbon composite of carbon plastic tapes and 1.21 for the prestressed one. Modification of the carbon composite during prestress molding leads to a 22% reduction in stress concentration on the surface of the carbon composite, increases strength by 37.8%, deformation by 25% and modulus of elasticity by 10.25%.

Research paper thumbnail of Study of macroplastic flow in surface layers of porous titanium nickelide by digital image correlation

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE “PHYSICAL MESOMECHANICS. MATERIALS WITH MULTILEVEL HIERARCHICAL STRUCTURE AND INTELLIGENT MANUFACTURING TECHNOLOGY”

The work presents a study the mechanical properties of porous titanium nickelide and to study the... more The work presents a study the mechanical properties of porous titanium nickelide and to study the evolution of deformation fields at the meso-and macroscopic level on the surface of porous titanium nickelide samples of different thicknesses by the method of correlation of digital images under uniaxial tension. Optical system Vic-3D allows to reveal the peculiarities of evolution in space and time of distributions of deformation fields. With a decrease in the thickness of the samples and with their tension from the averaged deformation over the working field of the sample by more than 0.005%, this leads to an enlargement of the characteristic size of local deformation regions in speckle patterns on the surface of the 3D framework of the porous material. Based on the analysis of the deformation curves two stages of deformation are distinguished. It was found that the values of the deformation hardening coefficient n depend on the sample thickness.

Research paper thumbnail of Aluminum Alloying Effect on Porous Nitinol Properties Obtained by Self-Propagating High-Temperature Synthesis

SSRN Electronic Journal, 2021

Research paper thumbnail of Features of the structural phase state of a weld produced by electron-beam welding in the submicrocrystalline grade 2 titanium alloy

MATEC Web of Conferences, 2018

This paper presents the results of structural studies for a welded joint of the Grade 2 titanium ... more This paper presents the results of structural studies for a welded joint of the Grade 2 titanium alloy in submicrocrystalline and microcrystalline states produced by electron beam welding when joining 2-mm-thick plates. Microhardness distribution patterns of the Grade-2 titanium alloy in micro- and submicrocrystalline states are identified in the weld zone and heat-affected zone. These patterns reflect a difference in structural phase states. It is assumed that one of the key factors affecting both the structural state and microhardness distribution in the weld zone and heat-affected zone during electron-beam welding is high concentration of oxygen atoms embedded into the crystal lattice of α–Ti-based solid solution.

Research paper thumbnail of Positron Spectroscopy of Nanodiamonds after Hydrogen Sorption

Nanomaterials, 2018

The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium c... more The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at the temperature of 243 K and the pressure of 0.6 MPa. The hydrogen saturation of nanodiamonds changes the positron lifetime. Increase of sorption cycle numbers effects the positron lifetime, as well as the parameters of the Doppler broadening of annihilation line. The electron-positron annihilation being a sensitive method, it allows detecting the electron density fluctuation of the carbon material after hydrogen saturation.

Research paper thumbnail of High-temperature structure formation in cement depending on curing time

AIP Conference Proceedings, 2017

The paper presents a comprehensive study of the quantitative phase composition of Portland cement... more The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement shows that the bulk structures of clinker phases are not involved in the process of hydration. Experiments demonstrate that the crystal lattices of these phases are highly stable, and their binding energy tends to increase with the rise in curing time. The atomic-binding energy in crystal lattices of alite and larnite ranges within (187.379…187.616) and (496.764…497.016) eV, respectively. A high level of the atomic-binding energy indicates to the dissolution occurring at the interface between the solid and liquid phases. A certain atomic re-arrangement inside the crystal lattices can be accepted within the interval of stability as well as a variation of the number of atoms in unit cells.The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement sho...

Research paper thumbnail of Study of deformations evolution in near-surface layers of adhesive joints

This paper presents the study of the evolution in situ of distribution of local deformations in n... more This paper presents the study of the evolution in situ of distribution of local deformations in near-surface layers in pads made of carbon lamellas under strain deformation. The specimens were produced from two face-to-face docked steel pads 120×40×4 mm and two carbon lamellas FibARM Lamel 120×40×1,2 mm joint using the adhesion 'FibARM Resin Laminate+". The strain tests were performed using the "INSTRON 3386" test bed with a maximum tension of 100 кN (10,19 тs). Optical measurement system VIC-3D was used to identify the evolution of deformations distribution in the near-surface layers. The VIC-3D system allowed obtaining the images that reflect the evolution of distribution of relative deformations iso-fields under different loads. In situ experimental research was conducted focused on strain deformations in specimens made of a layered composite: metal/adhesive/carbon lamella. A crack in the specimen was modeled, which allowed determining that with a growth of the overall deformation there develops an evolution of special structural elements from chaotic (along the whole lamella area) to localized ones with higher deformation values in the crack region. It was established that at higher levels of overall deformation in the crack region on the carbon lamella surface, the maximum deformation region with one extremum is divided by a narrow line of low deformation into two parts along the joint of steel plates. A limit deformation is identified.

Research paper thumbnail of The Structural and Phase State of the TiAl System Alloyed with Rare-Earth Metals of the Controlled Composition Synthesized by the “Hydride Technology”

Metals, 2020

The structural state and the quantitative phase analysis of the TiAl system, alloyed with rare-ea... more The structural state and the quantitative phase analysis of the TiAl system, alloyed with rare-earth metals synthesized using hydride technology, were studied in this work. Using the Rietveld method, the content of the major phases in the initial system Ti(50 at.%)–Al(50 at.%), as well as Ti(49 at.%)–Al(49 at.%), with alloying additions Ta, Y and Dy having a high accuracy was determined. The methods of scanning electron microscopy, transmission electron microscope and X-ray spectral microanalysis of the local areas of the structure for studying the distribution of alloying elements were used. The energies of lattices of separate phases were also determined after the full-profile specification. All the lattices of the identified structures (about 30) turned out to be stable. It was established that in the Ti(49 at.%)–Al(49 at.%) systems under study with alloying additions of metals Ta, Y and Dy, there were intermetallides composed of AlTi3, TiAl in the hexagonal, tetragonal and tricl...