Laser beam welding of a CoCrFeNiMn-type high entropy alloy produced by self-propagating high-temperature synthesis

Fiber laser beam welding of a CoCrFeNiMn-type high entropy alloy (HEA) produced by self-propagating hightemperature synthesis (SHS) was reported in this work. The SHS-fabricated alloy was characterized by both ∼2 times reduced Mn content in comparison with that of the other principal components and the presence of impurities including Al, C, S, and S

Patterns of economically safe restructuring of Russian industry

The purpose of the article is to propose the main patterns of restructuring (structural changes) of the Russian industrial economy. The task of the study is to reveal the essence and substantiation of each of the formulated patterns. The subject of the publication is the organizational and economic relations arising during the safe restructuring of the Russian industry. The methodology of the study proceeds from objectively existing, recurring, significant dynamic, static or combined relationships and dependencies of phenomena and processes of social production, which characterize the increase in the aggregate result of the country’s industrial system functioning. The main results are reduced to the definition of nine patterns of economically safe restructuring with the justification of each of them and the specification of their essence. Their scientific understanding is quite applicable both in educational institutions of the country in the study of economic theory and security, the restructuring of the industrial economy, and the economic practice of structural changes at all government levels. A general conclusion has been formed, expressing the content of the main patterns of safe industrial restructuring as an economic concept and its objective foundations

Regularities of the metallurgical industry restructuring process: Content, safety and regulation

The purpose of the work is to reveal the content, safety and regulation of the metallurgical industry restructuring. The objectives of the article are to generalize the theory and methods that characterize the essence of the designated industry restructuring regularities, the main directions of their safe implementation and regulation. The subject of the publication defines the organizational and economic relations arising during the implementation of the Russian metallurgy safe restructuring. The methodology of the study proceeds from objectively recurring significant relationships and dependencies that arise in the metallurgical industry restructuring process, the main link of its economy. The key results are reduced to determining a number of regularities of restructuring, its essence, features, priorities, clustering and ways of safe regulation by the state. Their scientific understanding is quite applicable both in educational institutions of the country when studying the theory and methodology of economic science, methods of restructuring of various sectors of the economy, and in real practice of structural changes at all levels of government. In conclusion, a number of findings are formed, reflecting both the content and safety of the restructuring of metallurgy and the corresponding laws, and the regulation of these processes

СВС-МЕТАЛЛУРГИЯ КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ НА ОСНОВЕ Nb–Si

Niobium-based composites doped with functional and alloying additives (Si, Hf, Ti, Al, etc.) have prospects for industrial applications such as aircraft engine building. Previously the authors demonstrated that such composites can be synthesized in autowave mode (combustion mode) using highly exothermic Nb2O5 mixtures with Al, Si, Hf and Ti. It was shown that hafnium actively participates in Nb2O5 reduction, and this makes it difficult to introduce it into the composite. This paper focuses on the possibility to synthesize Nb composites doped with a high amount of Hf using centrifugal SHS metallurgy. Experiments on a centrifugal unit under 40 g force demonstrated that reactive Hf replaced by its less reactive compounds Hf–Al or Hf–Ti–Si–Al in Nb2O5/Al mixtures enabled combustion in a steady frontal mode rather than in an explosive one. With the increasing size of Hf–Al granules (from 0–40 to 160–300 μm), the Hf content of resultant composites was found to grow from 1,3 to 3,8 wt.%. In case of Hf–Ti–Si–Al granules 1–3 mm in size introduced to the charge, the Hf content of synthesized composites based on niobium silicides attained a value of up to 8,1 wt.%. Electron microscopy and X-ray diffraction analysis were used to determine the integral composition and distribution of basic and doping elements in the structural components of synthesized composites as well as their phase composition. Composites with a maximum content of Hf (8,1 wt.%) contain three structural constituents: (1) a metal Nb–Si–Ti matrix; (2) intergrain boundaries containing Nb, Ti, and Al; and (3) hafnia-based inclusions. The XRD pattern showed the presence of three phases in the composite: Nb and Nb5Si3 solid solutions as well as minor amounts of Nb3Si.Композиционные материалы (КМ) на основе ниобия c функциональными и легирующими добавками (Si, Hf, Ti, Al и др.) имеют перспективу промышленного освоения в авиационном двигателестроении. Ранее авторами было показано, что такие КМ можно синтезировать в автоволновом режиме (режиме горения), используя высокоэкзотермические смеси Nb2O5 с Al, Si, Hf и Ti. Было обнаружено, что в волне горения гафний активно участвует в восстановлении Nb2O5, что усложняет его введение в КМ. Настоящая работа направлена на изучение возможности синтеза методами центробежной СВС-металлургии композиционных материалов на основе Nb с высоким содержанием Hf. В экспериментальных исследованиях, проведенных на центробежной установке под воздействием перегрузки 40 g, было показано, что замена активного Hf на менее активные его соединения Hf–Al или Hf–Ti–Si–Al в составе смесей Nb2O5/Al позволяет перевести горение смеси из взрывоподобного режима в режим стационарного горения. С увеличением размера гранул Hf–Al от 0–40 до 160–300 мкм в смеси содержание Hf в КМ возрастает от 1,3 до 3,8 мас.%. Введение в исходную шихту гранул Hf–Ti–Si–Al с размером частиц от 1 до 3 позволяет получать литые КМ на основе силицидов ниобия с содержанием Hf до 8,1 мас.%. Методами электронной микроскопии и рентгенофазового анализа определены интегральный состав и распределение базовых и примесных элементов в структурных составляющих литых КМ, а также их фазовый состав.Композиционные материалы с максимальным содержанием Hf (8,1 мас.%) содержат 3 структурных составляющих: (1) – основу, которая включает Nb, Si, Ti; (2) – межзеренные границы, содержащие Nb, Ti и Al; (3) – включения на основе оксида гафния. На рентгенограмме КМ выявлены 3 фазы: твердые растворы на основе Nb и Nb5Si3, а также небольшое количество Nb3Si

The ultraluminous GRB 110918A

GRB 110918A is the brightest long GRB detected by Konus-WIND during its 19 years of continuous observations and the most luminous GRB ever observed since the beginning of the cosmological era in 1997. We report on the final IPN localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a typical duration, a moderare $E_{peak}$ of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z=0.984, a huge isotropic-equivalent energy release $E_{iso}=(2.1\pm0.1)\times10^{54}$ erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity $L_{iso}=(4.7\pm0.2)\times10^{54}$erg s$^{-1}$. A tail of the soft gamma-ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. Swift/XRT and Swift/UVOT observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break. The post-break scenario for the afterglow is preferred from our analysis, with a hard underlying electron spectrum and ISM-like circumburst environment implied. We conclude that, among multiple reasons investigated, the tight collimation of the jet must have been a key ingredient to produce this unusually bright burst. The inferred jet opening angle of 1.7-3.4 deg results in reasonable values of the collimation-corrected radiated energy and the peak luminosity, which, however, are still at the top of their distributions for such tightly collimated events. We estimate a detection horizon for a similar ultraluminous GRB of $z\sim7.5$ for Konus-WIND, and $z\sim12$ for Swift/BAT, which stresses the importance of GRBs as probes of the early Universe.Comment: 22 pages, 20 figures, accepted for publication in Ap

Comparative investigation of the structure, phase composition, and mechanical properties of Ni-based high-temperature alloys manufactured by different methods

A comprehensive comparative study of the structure, phase composition, and mechanical properties of heat-resistant nickel-based Ni-Cr-(X) alloys produced by the methods of traditional metallurgy and self-propagating high-temperature synthesis (SHS metallurgy) is carrie

The Interplanetary Network Supplement to the Fermi GBM Catalog of Cosmic Gamma-Ray Bursts

We present Interplanetary Network (IPN) data for the gamma-ray bursts in the first Fermi Gamma-Ray Burst Monitor (GBM) catalog. Of the 491 bursts in that catalog, covering 2008 July 12 to 2010 July 11, 427 were observed by at least one other instrument in the 9-spacecraft IPN. Of the 427, the localizations of 149 could be improved by arrival time analysis (or triangulation). For any given burst observed by the GBM and one other distant spacecraft, triangulation gives an annulus of possible arrival directions whose half-width varies between about 0.4' and 32 degrees, depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. We find that the IPN localizations intersect the 1 sigma GBM error circles in only 52% of the cases, if no systematic uncertainty is assumed for the latter. If a 6 degree systematic uncertainty is assumed and added in quadrature, the two localization samples agree about 87% of the time, as would be expected. If we then multiply the resulting error radii by a factor of 3, the two samples agree in slightly over 98% of the cases, providing a good estimate of the GBM 3 sigma error radius. The IPN 3 sigma error boxes have areas between about 1 square arcminute and 110 square degrees, and are, on the average, a factor of 180 smaller than the corresponding GBM localizations. We identify two bursts in the IPN/GBM sample that did not appear in the GBM catalog. In one case, the GBM triggered on a terrestrial gamma flash, and in the other, its origin was given as uncertain. We also discuss the sensitivity and calibration of the IPN.Comment: 52 pages, 12 figures, 4 tables. Revised version, resubmitted to the Astrophysical Journal Supplement Series following refereeing. Figures of the localizations in Table 3 may be found on the IPN website, at ssl.berkeley.edu/ipn3/YYMMDD, where YY, MM, and DD are the year, month, and day of the burst, sometimes with suffixes A or

Integrating the Fermi Gamma-Ray Burst Monitor into the 3rd Interplanetary Network

We are integrating the Fermi Gamma-Ray Burst Monitor (GBM) into the Interplanetary Network (IPN) of Gamma-Ray Burst (GRB) detectors. With the GBM, the IPN will comprise 9 experiments. This will 1) assist the Fermi team in understanding and reducing their systematic localization uncertainties, 2) reduce the sizes of the GBM and Large Area Telescope (LAT) error circles by 1 to 4 orders of magnitude, 3) facilitate the identification of GRB sources with objects found by ground- and space-based observatories at other wavelengths, from the radio to very high energy gamma-rays, 4) reduce the uncertainties in associating some LAT detections of high energy photons with GBM bursts, and 5) facilitate searches for non-electromagnetic GRB counterparts, particularly neutrinos and gravitational radiation. We present examples and demonstrate the synergy between Fermi and the IPN. This is a Fermi Cycle 2 Guest Investigator project.Comment: 5 pages, 11 figures. 2009 Fermi Symposium. eConf Proceedings C09112