bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thirty years of collaboration and research from 1989 to 2019: a tribute to Ruslan Z. Valiev
Authors: Langdon T G 
Published: November 2019

Abstract
A visit to the Institute of Problems of Superplasticity of Metals in Ufa in 1989 initiated a cooperation and collaboration with Ruslan Valiev that has continued for the last thirty years. This collaboration started with fundamental investigations of superplasticity, such as the demonstration that intragranular slip is necessary to accommodate grain boundary sliding in conventional superplastic flow, but it was then extended to cover the processing and properties of a wide range of metals produced using severe plastic deformation to achieve exceptional grain refinement. Highlights included the publication of a first comprehensive review of equal-channel angular pressing (now with more than 3600 citations on Google Scholar) and co-authoring a textbook (Bulk Nanostructured Materials: Fundamentals and Applications, published by TMS/Wiley in 2014).
Progress in NanoSPD research through scientometric analysis
Authors: Safargalina Z , Alexandrov I V 
Published: November 2019

Abstract
In this paper, we use the scientometric approach based on the Web of Science Core Collection to analyze the data on publication activity in the area of nanostructured materials processed by severe plastic deformation (SPD) techniques on the following three main topics: ultrafine-grained materials, severe plastic deformation and bulk nanostructured materials. The results marked early 1990s as the starting period for first publications in question as well as their fast development. Pioneer works by Prof. Valiev and his laboratory at that time and their role in the growth of nanoSPD-related research were outlined.
The influence of the mode of interaction of compact samples made of nonpassivated iron nanopowders with air on their microstructure
Authors: Alymov M I , Seplyarskii B S , Vadchenko S G , Kochetkov R A , Rubtsov N M , Zelensky V A , Schukin A S 
Published: November 2019

Abstract
In this work, various modes of interaction (spontaneous ignition or a combustion mode) of compact samples made from nonpassivated iron nanopowders with air are found out. The experiments showed that the modes of interaction of the samples with air after their extraction from a weighing bottle depended on the media (argon or air), in which the weighing bottle was placed before extraction of the samples, as well as on the duration of the exposure of the weighing bottle in the air. It is shown that the process of interaction of the sample with air has a surface character; the inner layer of the sample contains unreacted nanopowder. The microstructure of the transverse fracture of the samples after spontaneous ignition and combustion represents a porous aggregation of agglomerates. Integral energy-dispersive analysis showed a higher content of oxygen in the near-surface layer of the sample about 300÷500 microns thick. The analysis of the microstructure of the fracture of a separate agglomerate showed the presence of a layer with an elevated oxygen content on the surface of the agglomerates. Particles in the agglomerates retain the dimensions of passivated iron nanopowders.
Microstructure evolution in a CuZr alloy and CP Ti processed by a novel technique of free bending in rotating rollers
Authors: Janeček M , Krajňák T , Veselý J , Minárik P , Preisler D , Stráský J , Raab A G , Raab G I , Asfandiyarov R N 
Published: November 2019

Abstract
A novel technique referred to as free bending in rotating rollers was employed to refine the initial structure and to produce gradient fine-grained microstructures in the Cu0.5Zr alloy and commercially pure titanium (CP Ti). A newly designed die allowing a continuous and repetitive movement of a workpiece through a set of rollers in a channel bent by 90 degrees was employed to produce a series of billets after different numbers of passes resulting in different strains imposed on the billet. Microstructure evolution with increasing number of passes was characterized by precise measurements of microhardness (HV) distribution along the cross section of individual billets. The heterogeneous distribution of HV observed after a single pass was transformed to almost a uniform one in the whole cross section of the billets after 8 passes. EBSD analysis and TEM observations revealed a significant microstructure refinement in both materials after the final stage of processing. A homogeneous microstructure with an average grain size of about 300 nm was observed in CP Ti, whereas the microstructure of the Cu0.5Zr alloy was not fully refined and exhibited a bimodal grain size distribution. The experimental results were compared with the theoretical modelling of strain distribution by FEM.
The effect of heat treatment on the structure and mechanical properties of additively manufactured stainless steels
Authors: Korznikova G F , Smirnov V V , Gunderov D V , Mulyukov R R 
Published: November 2019

Abstract
Selective laser sintering was applied for stainless steel samples additive manufacturing. It was found that in the as fabricated state, the samples consist of martensite and residual austenite, contained significant dislocation density and residual stresses. Additively manufactured samples had an ultrafine-grained structure with predominantly high angle grain boundaries and were free of crystallographic texture and residual porosity. The ultimate tensile strength of the as-built steel was 960 MPa. Annealing caused a decrease in residual austenite, but did not significantly affect the size and morphology of the grains. The ultimate strength after annealing increased markedly while maintaining plasticity.
Effects of nano and submicrocrystalline states under a wide range of loads
Authors: Naimark O B 
Published: November 2019

Abstract
The scale in nanomechanics (10−10−10−9 m) has a fundamental physical meaning and can be considered as a control parameter when considering qualitative changes in the properties of polycrystalline materials when the grain structure changes in a wide range of load intensities. The existence of this parameter can lead to effects beyond the scale, which are traditionally considered in mechanics, and are accompanied by the influence of quantum effects on the deformation properties and failure of materials. New ideas about submicrocrystalline and nano-scale structure of materials achieved by the use of high-resolution methods (synchrotron tomography, soft X-rays, nanoindentation) have led to qualitative changes in approaches to the study and description of the properties of materials, including biomaterials. This may provide new information on the processes of deformation and fracture at the micro- and nano-scale level and lead to new approaches in the design and evaluation of the reliability.
Mechanical properties and thermal stability of an ultrafine-grained near β titanium alloy
Authors: Naydenkin E V , Mishin I P , Ratochka I V , Lykova O N 
Published: November 2019

Abstract
Comparative studies of the structure, mechanical properties and thermal stability of an ultrafine-grained near β titanium alloy of the transition class Ti-5Al-5Mo-5V-1Cr-1Fe obtained by the methods of multiple pressing and radial-shear rolling with subsequent aging have been carried out. It is shown that as a result of multiple pressing, the formation of a homogeneous micro-duplex ultrafine-grained structure with an average grain (phase) size of ∼0.2 μm is observed. Radial shear rolling followed by aging leads to the formation of an inhomogeneous structure with precipitates of the α phase particles and a subgrain size of the β phase of about 0.5 μm inside which thin-acicular precipitates of the metastable α” phase are observed. Despite the smaller imposed plastic deformation and the larger size of grain-subgrain structure, alloy samples after radial-shear rolling and aging demonstrate higher strength properties at room temperature compared to the alloy obtained by multiple pressing (the ultimate strength of the alloy after these treatments is 1695 and 1600 MPa, respectively.) At the same time, the alloy obtained by the method of multiple pressing shows higher ductility and thermal stability of the mechanical properties due to the micro-duplex ultrafine-grained structure. The drop in strength as a result of annealing is due to the development of recrystallization in the case of the alloy after pressing and the dissolution of the strengthening α” phase in the case of the alloy after radial-shear rolling and aging.
Effect of frequency on plasma electrolytic oxidation of zirconium in pulsed unipolar mode
Authors: Parfenov E V , Mukaeva V R , Farrakhov R G , Saikiran A , Hariprasad S , Manoj P , Lokesh E , Rameshbabu N 
Published: November 2019

Abstract
Using the method of in situ impedance spectroscopy, an optimization of plasma electrolytic oxidation (PEO) was performed, and the influence of the pulse frequency was evaluated for the coating of Zr-1Nb alloy. It was shown that the in situ impedance modulus decreased with increasing the pulse frequency in a pulsed unipolar mode. Also, the protective properties of the coating improved with frequency; this was attributed to the increase in the uniform distribution of the microdischarges over the sample surface. As a result, the optimal frequency range of PEO was justified based on the impedance spectroscopy studies.
Structure of materials ultrasonically consolidated from coarse-grained and nanostructured plates of commercially pure copper
Authors: Parkhimovich N Yu , Yusupova N R , Nazarov A A 
Published: November 2019

Abstract
Ultrasonic consolidation of commercially pure copper plates with coarse-grained and ultrafine grained structures was carried out. Copper plates in both states were joined by ultrasonic welding using the same route. Consolidated samples were studied in a cross section parallel to the oscillation direction. The compressive strain value and the joint quality in relation to the initial structure of the material were studied. It is shown that the ultrasonic consolidation is a promising method of additive manufacturing using bulk nanostructured materials.
Nanocrystal formation and structure rejuvenation in Al-based alloys
Authors: Matveev D , Pershina E , Volkov N , Abrosimova G 
Published: November 2019

Abstract
Studies of the structural evolution of the group of Al-based amorphous alloys of Al-Ni-RE (RE = La, Y, Gd) systems showed that, under the combined action of heat and deformation on the structure, one may obtain samples with different crystal sizes and different fractions of the nanocrystalline phase. Under crystallization of a heterogeneous amorphous phase, the size of the nanocrystals is smaller, and their fraction is larger than under crystallization of a homogeneous amorphous phase. The use of cryogenic cycling method allows rejuvenating the amorphous phase in partially crystalline alloys.
Post-dynamic recrystallization of the Cu-0.6Cr alloy
Authors: Aksenov D A , Asfandiyarov R N , Raab G I , Raab A G 
Published: November 2019

Abstract
The results of the studying the transformation of structural parameters in the samples of the Cu-0.6Cr alloy during high-temperature free upsetting and subsequent cooling at different rates with the use of different media: liquid nitrogen, water and air are presented. Using EBSD and X-ray diffraction (XRD) analysis, we demonstrate that a decrease in the cooling rate of the samples of the Cu-0.6Cr alloy after a large deformation of e~2 at a temperature of 800-850 °C promotes the formation of smaller structural fragments, an increase in the dislocation density and a reduction in the fraction of high-angle boundaries.
Structure of deformed Al-based amorphous alloys
Authors: Matveev D , Pershina E , Postnova E , Fokin D , Aronin A 
Published: November 2019

Abstract
The structure of deformed Al-based amorphous alloys was studied by X-ray diffraction, scanning, transmission and probe electron microscopy. It has been found that the material in the shear bands has lower values of Young’s modulus and density. The shear band width is about 50 nm. In the band, no redistribution of the alloy components typical for phase separation is observed. The size of the regions with reduced Young’s modulus around the shear band is in the range from several tenths of a micron to 1 µm.
Study of the processing of long-length billets by continuous free bending
Authors: Asfandiyarov R N , Aksenov D A , Raab G I 
Published: November 2019

Abstract
This paper investigates the features of deformation processing by continuous free bending in rollers, aimed at enhancing the mechanical properties of long-length metallic billets without any change in their cross section. As the material for the investigation, we selected a chromium-zirconium bronze for electrical engineering applications, used, for example, for the production of contact wires that require high mechanical characteristics. Computer simulation reveals that during the processing by continuous free bending, a gradient field of accumulated strain is formed, with maximum values in the peripheral region and with minimum values in the center of the billet. It is found that during bending, by the 6th cycle the peripheral layers of the billet accumulate a strain of e~2, and the damage reaches a value of ~1. In the process of verification by means of a physical experiment, cracks emerge on the billet surface during the 6th cycle, confirming the simulation data. Structural analysis shows that during multi-cycle processing by this method, a gradient type of structure is formed. An important advantage of the processing by continuous free bending is the enhancement of the mechanical properties of long-length samples without any reduction in the cross-sectional area: e.g., after 4 processing cycles the ultimate tensile strength increased from 250±20 to 380±20 MPa, and the variation of the cross-sectional area was ~5-7%. The obtained results are in agreement with some principles of severe plastic deformation processing.
SEM and AFM analysis of the shear bands in Zr-based BMG after HPT
Authors: Astanin V , Gunderov D , Boltynjuk E , Ubyivovk E , Churakova A , Gunderova S 
Published: November 2019

Abstract
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 internal surfaces of two joint halves of an HPT-processed disk allowed to study the formation and accumulation of shear bands under an increased imposed strain. The maximum density of the shear bands is observed at the edges of the HPT samples and in areas adjacent to the upper anvils. The observed minimum shear band spacing is equal to 0.5 μm after HPT processing for 5 revolutions.
On strengthening of ultrafine grained austenitic steels subjected to large strain deformation
Authors: Belyakov A , Odnobokova M , Yanushkevich Z , Nazarova M , Kaibyshev R 
Published: November 2019

Abstract
Our current results on the structure-property relationship in ultrafine grained (UFG) austenitic steels, subjected to large strain deformation under conditions of cold to warm working are critically reviewed. Commonly, the grain size and dislocation density that evolve in UFG steels and alloys during large strain deformation depends sensitively on the processing conditions, i.e., temperature and strain rate. The grain size decreases, and the dislocation density increases with a decrease in deformation temperature. Therefore, a unique power-law relationship with a grain size exponent of -0.6 holds between the deformation grain size and the dislocation density. A power-law function between the grain size and dislocation density is obtained for UFG steels even after annealing. Thus, the yield strength of UFG steels can be expressed by a modified Hall-Petch-type relationship, which includes the dislocation strengthening, by using the grain size or dislocation density as a unique variable.
Influence of severe plastic deformation on the structure and mechanical properties of eutectic Al-Zn-Mg-Fe-Ni alloy
Authors: Brodova I G , Petrova A N , Akopyan T K 
Published: November 2019

Abstract
The structure and phase evolution of the new eutectic high strength aluminium alloy Nikalin were investigated under high pressure torsion (HPT) by several numbers of the revolution of the anvil. The chemical composition of the investigated Nikalin alloy was as follows: Al (base)– 7.22Zn–2.95 Mg–0.52 Fe–0.57 Ni–0.2 Zr. (wt.%). The initial material was a coarse grained cast ingot after homogenization. It was established that the HPT process resulted in the deformation dissolution of the nanosized T-phase precipitates and the formation of a supersaturated aluminum solid solution simultaneously with the strong refinement of the structure to the grain-subgrain size of 130-150 nm. Due to that, the yield stress of the HPT alloy increased by a factor of 1.5, the ultimate tensile strength increased by a factor of 1.4, while preserving good ductility of 6-7%. The observed effect of the additional supersaturated solution upon HPT relative to the homogenized state appeared upon post-deformation annealing at 140 °C. An increase in the microhardness of the HPT alloy due to the MgZn2 phase precipitation was observed at 0.5- hours of annealing.
Contribution of structural factors to the specific electrical resistance of nanostructured Cu-Cr-Zr alloy
Authors: Chembarisova R G , Sarkeeva E A , Alexandrov I V 
Published: November 2019

Abstract
The specific resistance of the nanostructured Cu-1.8wt.%Cr-0.8wt.%Zr alloy has been analyzed by means of analytical modeling. The contribution of different structural parameters to the specific resistance of the material has been estimated.
Microstructure and mechanical properties of the ultrafine-grained TiNi alloy after multiple martensitic transformations and subsequent aging
Authors: Churakova A A , Gunderov D V 
Published: November 2019

Abstract
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 Ti49.0Ni51.0 alloy, using as an example the examination of the microstructure, mechanical properties and fractography. Our studies show that preliminary thermal cycling leads to a significant increase in the density of dislocations that promote the intensification of the aging process and thereby enhance the strength and functional characteristics of the TiNi alloy in the ultrafine-grained state.
Comparative analysis of the microstructure and mechanical properties of an Al-Cu-Mg-Ag alloy peak-aged at relatively low and high temperatures
Authors: Gazizov M , Holmestad R , Kaibyshev R 
Published: November 2019

Abstract
The mechanical properties and microstructure have been investigated in the Al-4.35Cu-0.46Mg-0.63Ag-0.36Mn-0.12Ti-0.04Fe alloy (in wt. %) peak-aged at 150 °C and 190 °C. The yield stresses (YS) and the ultimate tensile strength (UTS) were insignificantly higher by 15 MPa and 5 MPa, respectively, after peak-aging at 150 °C for 24 h compared with 190 °C for 1.5 h. Elongation-to-failure (δ) was the same (~6%) in both states. Microstructure analysis showed great differences in the morphology of precipitates within grain/subgrain interiors, as well as in the structure of regions adjacent to grain boundaries (GBs). Relationships between strength/ductile properties and microstructure were discussed.
Features of mass transfer by N-crowdions in fcc Ni3Al lattice
Authors: Bayazitov A M , Dmitriev S V , Zakharov P V , Shepelev I A , Fomin S Yu , Korznikova E A 
Published: November 2019

Abstract
Crowdions being interstitial atoms located in closely packed atomic rows, play an important role in relaxation processes occurring in metals and alloys under severe external impacts effectively transferring mass and energy. Dynamics of crowdions motion is well studied for pure metals, while for intermetallic alloys this issue has not previously been addressed. It was earlier shown that the so-called N crowdion that involves more than one atom in its 1D motion is much more effective in frames of propagation path and excitation energy that 1-crowdion. In the present study, the motion of 1- and 2-crowdions in the Ni3Al intermetallic alloy, was studied by means of the molecular dynamics method. N-crowdion was excited by providing the same value of initial energy to N neighbouring atoms along the close-packed atomic row. It was shown that the studied crowdions can propagate along the biatomic close-packed row, but show strong instability when moving in monatomic close-packed directions. It has been established that 2-crowdions have a mean free path 2-2.5 times longer than 1-crowdions with the same initial velocity. It was also revealed that the mean free path of the nickel atom initiated crowdion than that initiated on the aluminium atom. The results suggest a higher efficiency of 2-crowdions in mass transfer in the Ni3Al intermetallic alloy. In further works, it is proposed to study the possibility of launching 2-crowdions by bombarding the crystal surface with biatomic molecules.
Evolution of microstructure and mechanical properties of Ti-based metal-matrix composites during high-pressure torsion
Authors: Ozerov M S , Klimova M V , Shigoleva E A , Vershinina T N , Ivanisenko Yu V , Stepanov N D , Zherebtsov S V 
Published: November 2019

Abstract
The microstructure and microhardness evolution of a Ti/TiB and Ti-15(wt.%)Mo/TiB metal-matrix composites (MMC) during high-pressure torsion (HPT) at 400 °C was studied. The composites were fabricated by spark plasma sintering of either hcp α-Ti with 10 wt.% of TiB2 or Ti with 13.5 wt.% of Mo (resulted in a bcc β-Ti matrix) and of 10 wt.% TiB2 powders mixtures at 1000 or 1200 °C, respectively. An increase in the dislocation density, a considerable decrease in the grain size in both hcp or bcc Ti matrix, and shortening of TiB whiskers were observed in the microstructures of the composites during HPT. After five revolutions, a nanostructure with a (sub) grain size of ~30 or ~55 nm was produced in Ti or Ti-15Mo matrix, respectively. The microhardness increased with strain from 452 HV in the initial state to 520 HV after 5 revolutions for Ti/TiB MMC and from 575 to 730 HV for Ti-15Mo/TiB MMC. The contributions of various hardening mechanisms to the composites were evaluated.
Anodic plasma electrolytic saturation of the Ti6Al4V alloy with nitrogen and oxygen
Authors: Kusmanov S A , Tambovskiy I V , Korableva S S , Belkin P N 
Published: November 2019

Abstract
The structure of the Ti6Al4V alloy, its microhardness, surface roughness, and wear and corrosion resistance after anodic plasma electrolytic saturation with nitrogen and oxidation of the surface were investigated. It was shown that an electrolyte containing ammonia and ammonium chloride provided the saturation of the alloy with nitrogen and oxygen and the formation of TiO2 with rutile structure and a nitrogen solid solution in the alloy. The treatment at 750 °C during 5 min results in an increase in microhardness up to 790 HV and a decrease in surface roughness by 1.4-fold owing to the anode dissolution of titanium. The dry friction coefficient of the samples after treatment at 700 °C can be 3.5-fold reduced through sliding with a speed of 0.144 and a load of 105 N. These regimes allow diminishing the wear rate of samples of titanium alloy after their wear testing by 2 orders of magnitude. Corrosion resistance in Ringer’s solution does not deteriorate after treatment at a low temperature, when an oxide layer forms on the surface.