Author
A. Yu. Istomina
Bio: A. Yu. Istomina is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Grain boundary diffusion coefficient & Grain boundary. The author has an hindex of 2, co-authored 3 publications receiving 15 citations.
Papers
More filters
TL;DR: Based on the recently proposed model of grain boundary diffusion, the available research data on grain-boundary diffusion of Co in W, and on emission Mossbauer studies of grain boundaries in polycrystalline W have been analyzed in detail as discussed by the authors.
Abstract: Based on the recently proposed model of grain-boundary diffusion, the available research data on grain-boundary diffusion of Co in W, and on emission Mossbauer studies of grain boundaries in polycrystalline W have been analyzed in detail. Using joint processing of primary data for tracer analysis and Mossbauer studies, all the parameters of grain-boundary diffusion of Co in W have been determined: the coefficient of grain-boundary segregation, coefficient of grain-boundary diffusion, and the diffusion width of the grain boundary.
15 citations
TL;DR: In this paper, the mechanism of grain boundary diffusion of Co in Mo and temperature dependences of segregation factor and grain boundary diffusivity have been determined based on the specified Fisher model.
Abstract: Grain boundary diffusion of Co in Mo has been studied by radiotracer analysis and emission Mossbauer spectroscopy. The experimental results are treated based on the specified Fisher model. The mechanism of grain boundary diffusion of Co in Mo and temperature dependences of segregation factor and grain boundary diffusivity have been determined.
3 citations
2 citations
TL;DR: In this article , the authors study the fine-grained complexity of the CFL reachability problem and present an overview of conditional lower bounds based on widely believed hypotheses, and then use the existing reduction techniques to obtain new conditional lower-bound on the problem.
Abstract: In this paper we study the fine-grained complexity of the CFL reachability problem. We first present one of the existing algorithms for the problem and an overview of conditional lower bounds based on widely believed hypotheses. We then use the existing reduction techniques to obtain new conditional lower bounds on CFL reachability and related problems. We also devise a faster algorithm for the problem in case of bounded path lengths and a technique that may be useful in finding new conditional lower bounds.
Cited by
More filters
TL;DR: In this article, the results on grain boundary studies in coarse-grained and nanostructured materials and on interlayer interfaces in multilayers are analyzed using Mossbauer spectroscopy.
Abstract: Publications on the studies of interfaces in metals by the methods of Mossbauer (nuclear gammaresonance) spectroscopy are reviewed. Physical principles of the Mossbauer effect, various methods of nuclear gamma-resonance (NGR) spectroscopy and the Mossbauer spectra parameters are considered. The available results on grain boundary studies in coarse-grained and nanostructured materials and on interlayer interfaces in multilayers are analyzed. Capabilities of application of absorption and emission Mossbauer spectroscopy as well as of conversion electrons Mossbauer spectroscopy (CEMS) are discussed.
32 citations
TL;DR: In this paper, the mechanical properties of the alloys are measured both during mixture processing and after mechanical alloying, and factors that facilitate the solubility of Co in Au, namely, increased processing pressure, cobalt concentration in a charge mixture, true strain, and temperature decreased to cryogenic level are identified.
Abstract: The mechanical alloying of Au–Co mixtures, which are systems with high positive mixing enthalpy, is studied following high-pressure torsion deformation at room and cryogenic temperatures. X-ray diffractometry in synchrotron radiation and scanning microscopy are used to investigate the sequence of structural changes in the course of deforming the mixtures up to the end state of the fcc substitutional solid solution based on gold. The mechanical properties of the alloys are measured both during mixture processing and after mechanical alloying. Microfractographic studies are performed. Factors that facilitate the solubility of Co in Au, namely, increased processing pressure, cobalt concentration in a charge mixture, true strain, and temperature decreased to cryogenic level have been identified.
13 citations
TL;DR: The proposed method for the assessment of the presence and nature of impurities and the quantitative evaluation of their distribution in semiconducting and insulating nanostructures is expected to find direct applications in nanotechnology, in the synthesis and quality assurance of thin films for spintronics and opto- and nanoelectronics.
Abstract: Magnetic and electrical properties of the nanostructured ZnO films are affected by the nonrandom distribution of impurities in the film due to segregation at grain boundaries (GBs) or extended defects. However, mapping the nature and distribution of the impurities in the film is not trivial. Here we demonstrate a simple, statistically relevant, and nondestructive procedure of quantitative determination of the paramagnetic impurities segregated at the GBs in nanostructured semiconducting and insulating films. From correlated electron paramagnetic resonance and transmission electron microscopy investigations, we determined the localization of trace amounts of Mn2+ ions, present as native impurities in a ZnO film deposited by magnetron sputtering at room temperature. In the as-deposited ZnO film, the Mn2+ ions were all localized in nanosized pockets of highly disordered ZnO dispersed between nanocrystalline columns. After the samples had been annealed in air at >400 °C, the size of the intercrystalline regio...
11 citations
TL;DR: In this article, the grain boundaries in polycrystalline molybdenum have been studied by emission Mossbauer spectroscopy on 57Co (57Fe) nuclei.
Abstract: Grain boundaries in polycrystalline molybdenum have been studied by emission Mossbauer spectroscopy on 57Co (57Fe) nuclei. It has been shown that Co atoms diffuse along the grain boundaries by the interstitial mechanism. The states of Co atoms in grain boundaries and in near-boundary regions of the crystallites have been analyzed. The values of the effective diffusion coefficient in the subboundary regions of the crystallites have been estimated. The temperature dependence of the grain-boundary segregation factor of Co in Mo has been determined.
8 citations
TL;DR: In this article, a radiometric layer-by-layer analysis has been used to study the grain-boundary diffusion of Co in sub-microcrystalline Mo produced by severe plastic deformation using high-pressure torsion.
Abstract: Radiometric layer-by-layer analysis has been used to study the grain-boundary diffusion of Co in submicrocrystalline Mo produced by severe plastic deformation using high-pressure torsion. It has been found that, under severe plastic deformation, nonequilibrium grain boundaries have been formed, which are ultrafast diffusion paths. During annealing, the recovery of nonequilibrium grain boundaries takes place. The properties of boundaries that underwent the recovery were shown to be close to those of boundaries originated by recrystallization in coarse-grained Mo. As the annealing temperature increases, the fraction of nonequilibrium boundaries decreases; and beginning from 823 K, there are no more nonequilibrium boundaries in the structure.
6 citations