Anna Churakova

Anna Churakova
Ufa Scientific Center of the Russian Academy of Science | USC RAS · Institute of Molecule and Crystal Physics

Doctor of Philosophy

About

76
Publications
9,093
Reads
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496
Citations
Citations since 2017
59 Research Items
434 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
Additional affiliations
January 2014 - present
Ufa State Aviation Technical University
Position
  • Researcher
November 2013 - present
Ufa Scientific Center of the Russian Academy of Science
Position
  • PhD
November 2013 - present
Institute of Molecule and Crystal Physics - Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences (IMCP UFRC RAS)
Position
  • Researcher
Education
September 2019 - July 2022
Ufa State Petroleum Technological University
Field of study
  • Anticorrosive protection of equipment and structures
September 2007 - July 2012
Ufa State Aviation Technical University
Field of study
  • nanomaterials

Publications

Publications (76)
Poster
Full-text available
Article
This paper presents comparative studies of the structural and mechanical properties of the new Ti–10Mo–8Nb–6Zr β-Ti alloy subjected to traditional cold rotary forging and equal channel angular pressing (ECAP) at 250 °C. The main phase in the initial hardened state after forging and ECAP is the BCC β phase. A broadening of the β phase X-ray lines an...
Article
Full-text available
Biomedical Ti-18Zr-15Nb (at.%) shape memory alloy was subjected to a low-temperature equal channel angular pressing (ECAP) at 200 °C for three passes and post-deformation annealing (PDA) in the 400–650 °C temperature range for 1 to 60 min. It was observed that ECAP led to the formation of an inhomogeneous highly dislocated substructure of β-phase w...
Conference Paper
The effect of thermal cycling on the structure of TiNi alloy in coarse-grained (CG) and ultrafine-grained (UFG) states is investigated. Thermodynamic aspects of martensitic transformations, changes in the entropy and energy of the process are considered. The change in the dissipation energy determines the change in the hysteresis of transformations...
Conference Paper
The team of the Sao Paolo University (Brazil) developed a new β-Ti alloy Ti10Mo8Nb6Zr, which is perspective as material for medical implants. The structure and micro-hardness of titanium alloy Ti10Mo8Nb6Zr after high pressure torsion were studied. The XRD analysis showed that β-phase was the main phase of Ti10Mo8Nb6Zr alloy in the initial state. Af...
Article
Full-text available
The data on the study of mechanical properties of cylindrical specimens of Al alloy 6101 in different states under static tension at room temperature are presented. The specimens were tested after natural aging, artificial aging, and ECAP. The surface of fractures of these specimens was also investigated using an electron microscope, and a chemical...
Article
Full-text available
A new efficient method was used to find that in the case of high-pressure torsion of commercially pure titanium, accumulation of shear strain in Ti does not occur due to slippage of anvils. Despite this, micro-hardness increases as the number of turns n increases, and Ti structure is refined more intensively. High-pressure torsion is accompanied by...
Article
Full-text available
This article studies the corrosion behavior of the TiNi alloy in the coarse-grained and ultrafine-grained states. The study of the influence of the initial microstructure on the corrosion behavior of the TiNi alloy was carried out by the gravimetric method in the NaCl and H 2 SO 4 solution for a month. Studies was shown that as a result of the acti...
Article
Effect of ECAP at 250 °C and annealing on structure and mechanical properties of the Ti-18Zr-15Nb biomedical alloy has been studied. The XRD and TEM data shows that ECAP leads to the formation of a predominantly nanocrystalline structure composed of equiaxed structure elements (grains and subgrains) of β-phase whose diameter ranges from 20 to 100 n...
Article
Full-text available
The strain γ processing at high-pressure torsion (HPT) deformation for many hard materials is really much smaller than expected. This is a result of slippage of sample surface and surface of anvils. In this context, the authors develop a new method- “accumulative high-pressure torsion” (ACC HPT). This method enables producing much higher true strai...
Article
Full-text available
In this article, the microstructure and mechanical behavior of the Ti49.1Ni50.9 alloy with a high content of nickel in a coarse-grained state, obtained by quenching, ultrafine-grained (obtained through the equal-channel angular pressing (ECAP) method) and nanocrystalline (high pressure torsion (HPT) + annealing), were investigated using mechanical...
Article
Full-text available
Studies of the influence of ECAP on the structure and properties of the metastable β -Ti alloys Ti18Zr15Nb and Ti10Mo8Nb6Zr have been carried out. The XRD data shows that the BCC β is the main phase in the initial alloys and alloys after ECAP. As a result of ECAP, the strength and yield stress of the alloys increases significantly due to the refine...
Article
Full-text available
As revealed by studies, in the process of high-pressure torsion of hard or work-hardenable metals and alloys, including bulk metallic glasses, the actual produced strain is much smaller than the expected one. The authors proposed a new technique called “accumulative high-pressure torsion” for producing high strains in hard materials, including bulk...
Article
Full-text available
The paper reports on the studies of the effect of thermal cycling on the microstructure of the Ti - 50.8 at. % Ni alloy in coarse-grained and ultrafine-grained states, mechanical properties, and calculation of contributions to hardening in the studied states. The comparison of the calculated and experimental values of the yield stress in the TiNi a...
Article
Full-text available
High-pressure torsion allows one to achieve high strains of bulk metal glasses without their destruction. The article presents the results of studies on the effect of high-pressure torsion on the amorphous alloys of the same composition but obtained in different ways: in a form of a bulk plate and a melt-spun ribbon. It is shown that the degree of...
Article
Effect of HPT and accumulative HPT on the Ti18Zr15Nb biomedical alloy has been studied. According to the XRD and TEM data, the β-phase is a main phase in the alloy both in the initial state and after processing by HPT and accumulative HPT. The β-phase X-ray line width after HPT processing, and especially after ACC HPT processing has drastically inc...
Article
The microstructure and mechanical properties of the ultrafine-grained Ti–50.8 at.% Ni alloy after thermal cycling treatment with the number of cycles up to 250 was investigated. A fractographic analysis of the samples after tensile tests was carried out. The fracture pattern of the alloy in the UFG state has a viscous character with microdepths on...
Article
Full-text available
The article were discussed the effect of multiple martensitic transformations with a different number of cycles on the functional characteristics, microstructure and mechanical properties of the TiNi alloys in different structural states and chemical compositions. As a result of multiple martensitic transformations, the accumulation of defects and...
Article
Full-text available
The paper was investigated the effect of preliminary multiple martensitic transformations on the microstructure and mechanical and functional stability during subsequent annealing in the range of aging temperatures of the Ti 49.051.0 alloy in the coarse-grained state. The structure in the initial state has an austenitic structure with a grain size...
Article
Zr52.5Cu17.9Al10Ni14.6Ti5 (Vit105) Bulk metallic glass is processed by High-Pressure Torsion up to 30 rotations at room temperature, showing simultaneous enhancement of both strength (2023 MPa) and ductility (0.45%). Nano-crystal precipitates with an average size of 45 nm inside the amorphous matrix are observed after 30 turns HPT. Free volume incr...
Article
Full-text available
Vit105 (Zr52.5Cu17.9Ni14.6Al10Ti5 at. %) bulk metallic glass samples were processed by high-pressure torsion and accumulative high-pressure torsion. By DSC, XRD and SANS methods it was shown that accumulative high-pressure torsion allows for achieving high real strains and leads to an increase in the free volume and significant transformation of th...
Article
In this paper, we investigated the microstructure of the Ti-50.7 at.% Ni alloy after multiple martensitic transformations and subsequent aging at a temperature of 400 °C in different states. We studied the features of the formation of Ti3Ni4 nanoparticles and nanotwins I type depending on the initial microstructure in the Ti-50.7 at.% Ni alloy. It...
Article
Full-text available
The influence of multiple martensitic transformations on the functional properties and microstructure of the equiatomic TiNi alloy is considered. An analysis of mechanical tests showed that in the CG and UFG state in the Ti 50.0 Ni 50.0 alloy as a result of thermal cycling with an increase in the number of cycles, a monotonic increase in the yield...
Article
Full-text available
The influence of thermal cycling (TC) with a large number of cycles on the microstructure, the parameters of martensitic transformations (MTs), and the mechanical properties of a Ti-50.8 at.% Ni shape-memory alloy in coarse-grained (CG) and ultrafine-grained (UFG) states was investigated. The effect of microstructural and mechanical stability was f...
Article
Full-text available
The stress-strain diagrams and the distribution of triaxial stresses, taking into account the difference in geometry for various structural states in Al-6101 under static loading, are analyzed in this paper.
Article
Full-text available
The influence of thermal cycling in the temperature range of B2-B19’ martensitic transformations on the TiNi alloy structure and properties are studied. The level of properties, obtained as a result of mechanical tests and measurements of microhardness, obtained in the process of thermal cycling, remains stable during soaking at room temperature in...
Article
Full-text available
The influence of thermal cycling in the temperature range of B2-B19’ martensitic transformations on the TiNi alloy structure and properties are studied. Different states are considered, namely the initial coarse-grained (CG) state, the ultrafine-grained (UFG) state after ECAP, the state after ECAP and cold upsetting by 30%. It is shown that, as a r...
Article
Full-text available
The mechanical behavior of the coarse-grained Ti 49.14 Ni 50.86 alloy after multiple martensitic transformations B2-B19’ was investigated. A fractographic analysis of the samples after mechanical tests was carried out. The fracture pattern of the Ti 49.14 Ni 50.86 alloy in the coarse-grained state has a viscous and heterogeneous character with micr...
Article
Full-text available
In this paper, we investigate the effect of preliminary thermal cycling in the temperature range of martensitic transformation on the aging processes in the ultrafine-grained Ti 49.0 Ni 51.0 alloy, using as an example the examination of the microstructure, mechanical properties and fractography. Our studies show that preliminary thermal cycling lea...
Article
Full-text available
The surface relief formed by shear bands in bulk metallic glasses (BMG) under high-pressure torsion (HPT) has been investigated by the method of scanning electron microscopy (SEM) and atomic force microscopy (AFM). For this purpose, two halves of disks of the bulk metallic glass were jointed together and processed by HPT. The SEM examination of the...
Article
Full-text available
The effect of high-pressure torsion (HPT) on the structure and mechanical properties of a Zr-based bulk metallic glass (BMG) was investigated. The structure of the BMG changes significantly after HPT processing. In tensile tests, the BMG samples before and after HPT processing are brittle under a stress of about 1700 MPa. For the first time, three-...
Article
Studies show that with the HPT of bulk metallic glass, the actual achievable strain is significantly lower than the one predicted by the equation γ=2πnR/h. Such a discrepancy can be explained by the effect of “slippage” during the HPT. The authors proposed a new method − “accumulative HPT” − to achieve a high strain in hard materials, including BMG...
Article
High‐pressure torsion was used to consolidate the melt‐spun Cu50Zr50 amorphous ribbons. The high‐pressure torsion processing was conducted varying the strain by using different numbers of anvil rotations. Optical and transmission electron microscopy, X‐ray diffraction were used to study the effect of processing regimes on consolidation and structur...
Article
The parameters of shear band evolution with deformation were examined in the Vit105 bulk metallic glass. For this purpose, two halves of disks of the bulk metallic glass were joined together and processed by high-pressure torsion for various strains: from compression without rotation, to rotation for 5 revolutions. The discrepancy between the exper...
Article
Full-text available
The effect of multiple martensitic transformations on the microstructure and thermodynamic parameters of the alloy of the TiNi system was investigated. It was shown that in the Ti 50 Ni 50 alloy, with an increase in the number of thermal cycles with rapid heating and cooling up to n = 100, a consistent increase in the dislocation density occurs, an...
Article
Full-text available
Influence of thermomechanical treatment (deformation, thermal cycling treatment in the temperature range of martensitic transformations B2-B19’) on the TiNi alloys’ mechanical behaviour and fracture was studied. Different states were considered, they are initial coarse-grained (CG), ultrafine-grained (UFG) after ECAP (with a grain size of 200 nm),...
Article
Full-text available
The melt-spun (MS) Ti50Ni25Cu25 alloy and the Zr62Cu22Al10Fe5Dy1 bulk metallic glass (BMG) were subjected to high pressure torsion (HPT). X-ray diffraction (XRD) measurements show a shift of the first diffraction halo to a low angle after HPT processing, which corresponds to an increase in the values of the radius of the first coordination sphere a...
Article
Full-text available
The effect of coarse-grained (CG) and ultrafine-grained (UFG) structures processed by equal channel angular pressing on the formation and features of the surface relief during mechanical tensile tests at room and elevated temperatures was studied. The formation of the UFG structure leads to a significant increase in strength, but the ductility decr...
Article
Full-text available
The Zr62Cu22Al10Fe5Dy1 bulk metallic glass (BMG) was subjected to high pressure torsion (HPT) at room temperature and at 150 °C. XRD shows a shift of first amorphous halo towards a low angles, which corresponds to an increase in the first coordination sphere radius and an increase in free volume content approximately by 0.44 % and 0.74 % after HPT...
Article
The amorphous Ti 50 Ni 25 Cu 25 alloy was subjected to high pressure torsion (HPT) processing. TEM studies revealed in the structure of the HPT-processed samples the presence of nanocrystals with a size of about 5 nm and amorphous clusters with a size of about 10-30 nm. Atomic force microscopy (AFM) was used to study the surface morphology of foils...
Article
Comprehensive studies on the impact of multiple martensitic transformations B2‐B19′ on the structure and properties of ultrafine‐grained and nanocrystalline titanium‐nickel alloys are implemented. It is shown that in coarse‐grained, ultrafine‐grained and nanocrystalline titanium‐nickel alloys consecutive changes in the structure and properties take...
Article
The Zr62Cu22Al10Fe5Dy1 bulk metallic glass (BMG) was subjected to high pressure torsion (HPT) at room temperature. The state after HPT processing demonstrates presence of large number of heterogeneities in amorphous structure – shear bands. Nanoindentation was used to study the effect of HPT processing on deformation behavior and strain rate sensit...
Article
Full-text available
Ti 49 Ni 51 Сплавы на основе никелида титана являются известными функциональными материалами с эффектами памяти формы (ЭПФ). Механические испытания на растяжение показывают, что при старении исходного закаленного сплава предел прочности достигает наибольшего значения при старении при 400°С, что обусловлено выделением упрочняющих частиц при данных т...
Article
The article presents the results of the study on the mechanical behavior of ultrafine-grained (UFG) and nanocrystalline (NC) TiNi alloys produced by severe plastic deformation (SPD), using the techniques of high pressure torsion (HPT) and annealing. The features of the microstructure and deformation behavior of the NC and UFG alloy have been studie...
Article
Using the methods of transmission electron microscopy (TEM), X-Ray diffraction (XRD) and tensile mechanical testing, comparative studies of the effect of thermal cycling on the structure and properties of the coarse-grained (CG) and ultrafine-grained (UFG) alloy Ti50Ni50 are performed. It is found that under the action of repeated thermal cycling,...
Article
Special TEM procedure is used to study in detail the microstructure of the melt-spun (MS) amorphous alloy Ti50Ni25Cu25 subjected to high-pressure torsion (HPT). The cross section of an HPT-processed disc-shaped sample is studied. Groups of shear bands (SBs) are revealed on the lamellae cut from the HPT-processed samples. Nanocrystals form directly...
Article
Full-text available
This paper examines a technique for producing a TiNi alloy with an ultrafine-grained structure and enhanced mechanical characteristics. It is demonstrated that the use of the ECAP-Conform technique enables producing TiNi alloy samples with an ultimate tensile strength of up to 1300 MPa and a rather high level of ductility. Studies show that in this...
Article
The microstructure and mechanical properties of the Zr62Cu22Al10Fe5Dy1 bulk metallic glass (BMG) processed by high pressure torsion (HPT) at temperatures of 20° and 150°С were investigated. Transmission electron microscopy and XRD studies did not reveal any structural transformations. The material in both initial amorphous state and after HPT proce...
Article
This article is devoted to studying the influence of thermocycling in the range of temperatures of the thermoelastic martensitic transformation B2–B19' on the microstructure, the temperatures of the martensitic transformations, and the mechanical properties of the equiatomic alloy Ti50Ni50 in the coarse-grained (CG) and ultrafine-grained (UFG) stat...
Article
The effect of high pressure torsion (HPT) on the microstructure of Cu-Fe 36 wt.% alloy has been studied. The initial Cu-Fe alloy has a dendritic structure, the length of dendrites is up to 100 μm. As a result of HPT (20 anvil revolutions at 400 °C) a nanostructural state is formed. The average size of the Cu and α-Fe grains is 60 and 35 nm correspo...
Article
Full-text available
The mechanical properties, strain rate sensitivity (m) and deformation activation volume (ΔV) are investigated at the experimental temperatures from 20 to 400°С in a Ti50Ni50alloy in a coarse-grained (CG) state with the austenite grain size D = 200 μm and in an ultrafine-grained (UFG) state with D = 700 μm following an ECAP treatment. It is observe...
Article
Full-text available
The influences of thermal cycling treatment in the temperature range of B2-B19 martensitic transformations (-150 to 150 °C) on the TiNi alloy structure and properties were studied. Different states named the initial coarse-grained (CG) state, the ultrafine-grained (UFG) state after ECAP (with a grain size of 200 nm), the state after ECAP and cold u...
Article
The amorphous melt-spun (MS) Ti50Ni25Cu25 alloy is subjected to high-pressure torsion (HPT) at temperatures of 20-150 °C. The bright-field (BF) TEM images of the alloy change as a result of HPT processing, the view of the bright-field image depends on the temperature of HPT processing. HPT processing leads to a decrease in the energy of structural...
Article
Two TiNi alloys, Ti49.4Ni50.6 and Ti50Ni50, are subjected to equal-channel angular pressing (ECAP) resulting in the formation of a homogeneous ultra-fine grained microstructure. Tensile tests and strain rate jump tests are carried out in the temperature range of 25-400 °C to measure mechanical properties and strain rate sensitivity of both alloys b...
Conference Paper
Full-text available
TiNi alloys are widely known materials with the shape memory effect (SME) and superelasticity. One of the application areas for TiNi alloys is endodontic instruments for the treatment of root canals – "files". Fabrication of ultrafine-grained (UFG) and nanostructured (NS) states by severe plastic deformation (SPD) techniques in TiNi alloys is a pro...
Conference Paper
Full-text available
The effect of high pressure torsion (HPT) on the microstructure evolution of Cu-Fe 36% wt alloy has been studied. The initial Cu-Fe alloy has a dendritic structure, the length of dendrites is up to 100 µm. As a result of HPT (20 anvil rotations at 400 ºC) the refinement of a-Fe dendrites occurs, and a microstructure with Fe inclusions with a size f...
Conference Paper
Full-text available
The object of the present study is the CuFe alloy. The interest to this alloy was dictated by its application as anodes for aluminum producing [1]. The effective way to increase the properties of these anodes, such as thermal stability and corrosion resistance, is to make changes in the structure. It is known that a perspective way to improve prope...
Article
Electron microscopy, X-ray diffraction, tensile tests, and measurements of internal friction (IF) have been used to study the transformation of the structure and properties of commercial Grade-4 titanium subjected to deformation using equal-channel angular pressing combined with the Conform process (ECAP-Conform), drawing, and subsequent annealing....
Article
Long-length ultrafine-grained (UFG) Ti rods are produced by equal-channel angular pressing via the conform scheme (ECAP-C) at 200 °C, which is followed by drawing at 200 °C. The evolution of microstructure, macrotexture, and mechanical properties (yield strength, ultimate tensile strength, failure stress, uniform elongation, elongation to failure)...
Article
Full-text available
The article represents results of influence of different severe plastic deformation (SPD) techniques on TiNi alloys. It is demonstrated that strength and shape memory effect (SME) of TiNi can be significantly enhanced due to formation of ultrafine-grained (UFG) and nanocrystalline (NC) structures by SPD. Influence of equal channel angular pressing...
Article
Full-text available
TiNi после термоци-клической обработки, а также обнаружено увеличение плотности дислокаций в УМЗ TiNi после ТЦО. Ключевые слова: никелид титана, термоциклирование, равно-канальное угловое прессование, дифференциальная сканиру-ющая калориметрия. The thermocycling of samples of nickel-titanium in the initial coarse-grained (CG) state and in the ultra...
Article
Full-text available
Nanocrystalline (NC) Ti49.4Ni50.6 alloy with the grain size of 20-100 nm has been successfully produced using high pressure torsion (HPT) and annealing. The ultra fine grained (UFG) structure with the grain size of 300 nm in Ti49.4Ni50.6 alloy has been produced using equal channel angular pressing (ECAP). The mechanisms of deformation behavior of t...

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Project (1)
Project
This Project will summarize entire research and development related to TiNi-based materials. Special focus would be paid to possible practical applications of these alloys. We are looking for partnerships and formation of an excellent project consisting of complementary partners that will help us to exchange the most important information regarding recent research and applications.