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Influence of inhomogeneity of grain-boundary region of nanocristalline materials on elastic properties

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广东有色金属学报 2005年第2期15卷 164-167页

作者： Stepanov Y.N. Alymov M.I. baikov institute of metallurgy and materials sciences ras Moscow Russia

Experimental data indicate that Young’s modulus of materials decreases with the decreasing of the grain size. Obviously, the primary factor of this decrease is presence of grain-boundary region, which Young’s modulus other than in the bulk of crystallites. There is a set of various expressions for calculation of Young’s modulus of polycrystals, obtained under the assumption, that it is possible to consider a polycrystal as a composite consisting of a crystalline matrix and a intercrystalline layers (grain-boundary region). Calculations showed incorrectness of application of a majority of these expressions and a large error in the calculations for the nanocrystalline materials. By us, on the basis of the same assumptions, is also obtained analytical expression for calculating Young’s modulus of materials with grain size more than 30 nm, which is more exact, than all *** is necessary to consider under the calculation of effective Young’s modulus nanocrystalline materials with grain size of less than 30nm, that grain-boundary region itself is not uniform. It is reliably established, that the triple joints of grain boundaries have a structure and properties, different from the structure and the properties of grain boundaries, which these joints connect. For nanocrystalline materials the volume fraction of the triple joints in the grain-boundary region can reach 50% and even more. Therefore assumption was made, that the nanocrystalline materials should be represented as consisting of three phases (triple joints, grain boundary between the triple joints and crystallite). On the basis of this idea is obtained analytical expression for calculating of Young’s modulus nanocrystalline materials. The analysis shows that Young’s modulus calculated by this analytical expression coordinated with the theory and the experiment.

关键词：弹性体多相性结构性能铸锭工艺钢

Correction Methods for Quantitative EPMA Based upon φ(pz) Curve Fitting and Their Performance for Light Elements

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电子显微学报 1991年第2期 192-194页

作者： A.I.Kozlenkov baikov institute of metallurgy the USSR Academy of Sciences

In the conventional ZAF-correction procedure atomic number, absorption, andfluorescence effects are calculated separately and then combined to provide the overallcorrection factor for quantitative electron-probe microanalysis (EPMA). The atomicnumber correction is determined by direct calculation of the number of ioniationsproduced by the incident electron in the target, while the X-ray depth distributionfunction, Φ(ρz), in the approximate form given by Philibert, is used only to obtain

关键词： EPMA pz Curve Fitting and Their Performance for Light Elements

Influence of ZrO_(2)/SiO_(2) nanomaterial incorporation on the properties of PEO layers on Mg-Mn-Ce alloy

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Journal of Magnesium and Alloys 2022年第2期10卷 552-566页

作者： D.V.Mashtalyar I.M.Imshinetskiy K.V.Nadaraia A.S.Gnedenkov S.L.Sinebryukhov A.Yu.Ustinov A.V.Samokhin S.V.Gnedenkov institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok 690022Russian Federation Far Eastern Federal University Vladivostok 690922Russian Federation A.A.baikov institute of metallurgy and materials Science Russian Academy of SciencesMoscow 119991Russian Federation

The properties of coatings formed on the MA8 magnesium alloy by the plasma electrolytic oxidation in electrolytes containing mechanical mixture of zirconia and silica nanoparticles in concentrations of 2,4 and 6 g/l have been *** has been established by SEM,EDS,and XPS that ZrO_(2)/SiO_(2)nanoparticles successfully were incorporated into the ***-Raman spectroscopy showed the presence of ZrO_(2)in tetragonal and monoclinic forms in the PEO-coating composition as well as Mg_(2)SiO_(4) in tetrahedral configuration uniformly distributed in the outer part of *** coatings significantly reduce corrosion current density in comparison with bare Mg alloy and base PEOlayer(from 2.4×10^(–7)A/cm^(2) for base PEO layer to 0.7×10^(–7)A/cm^(2) for coatings with nanoparticles).It has been found that the presence of solid nanoparticles in the composition of coating has a positive effect on their hardness(this parameter was increased from 2.1±0.3 GPa to 3.1±0.4 GPa)and wearproof(the wear was reduced from(4.3±0.4)×10^(–5)mm^(3)/(N×m)to(3.5±0.2)×10^(–5)mm^(3)/(N×m)).

关键词： Plasma electrolytic oxidation Composite coatings Nanoparticles Zirconia Silica Protective coatings

Miniaturized disk bend test-a new techniquefor monitoring the changes of mechanicalproperties of structural materials operatingin extreme conditions

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广东有色金属学报 2005年第2期15卷 643-647页

作者： Tsepelev A.B. A.A.baikov institute of metallurgy and materials science of ras Moscow119991 Russia

Method of Miniaturized Disk Bend Test (MDBT) originally designed for the tests of irradiated materials is a convenient technique for monitoring the degradation of mechanical properties of structural materials operating in extreme conditions. A small size of specimens (disks with 3 mm in diameter and 0.1-0.3 mm in thickness) as well as possibility to use the standard equipments for tension and/or pressure tests allow minimizing the financial charge for application of this method in practice and enable to keep up in the real time with (watch on) the changes of materials mechanical properties induced by the effect of unfavorable environment. Wide application of MDBT or other methods for miniaturized specimen tests does possible to inspect on the fly the changes of strength and ductility of the materials, and, of the expense of it, to prevent an alert conditions caused by the materials degradation, for instance, catastrophic *** the paper, methodical aspects of MDBT technique application for estimation of structural materials mechanical properties have been considered. By the example of own results and literature data, the possibilities of MDBT method are demonstrated as well as the correlation of obtained from this technique parameters with the standard mechanical properties such as strength, yield stress and ductility of metals.

关键词：结构材料机械性能柔软性强度温度

High-purity rare-earth metals: preparation, properties, and application

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广东有色金属学报 2005年第2期15卷 332-335页

作者： Kol chugina N.B. Burkhanov G.S. Chistyakov O.D. Burkhanov Yu.S. baikov institute of metallurgy and materials Science Russian Academy of Sciences Moscow Russia

In recent years, the ever-growing interest of investigators to the study of rare-earth metals REM) is observed owing to unique properties of the metals and potential uses in electronics, laser technology, space techno... 详细信息

关键词：稀土金属纯度 REM 显微结构

Discovery of carbon-based strongest and hardest amorphous material

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National Science Review 2022年第1期9卷 25-35页

作者： Shuangshuang Zhang Zihe Li Kun Luo Julong He Yufei Gao Alexander V.Soldatov Vicente Benavides Kaiyuan Shi Anmin Nie Bin Zhang Wentao Hu Mengdong Ma Yong Liu Bin Wen Guoying Gao Bing Liu Yang Zhang Yu Shu Dongli Yu Xiang-Feng Zhou Zhisheng Zhao Bo Xu Lei Su Guoqiang Yang Olga P.Chernogorova Yongjun Tian Center for High Pressure Science (CHiPS) State Key Laboratory of Metastable Materials Science and Technology Yanshan University Key Laboratory for Microstructural Material Physics of Hebei Province School of Science Yanshan University Department of Engineering sciences and Mathematics Lule a University of Technology Department of Physics Harvard University Center for High Pressure Science and Technology Advanced Research Department of materials Science Saarland University Key Laboratory of Photochemistry Institute of Chemistry University of Chinese Academy of Sciences baikov institute of metallurgy and materials Science Russian Academy of Sciences

Carbon is one of the most fascinating elements due to its structurally diverse allo tropic forms stemming from its bonding varieties(sp,sp~2 and sp~3).Exploring new forms of carbon has been the eternal theme of scientific ***,we report on amorphous(AM) carbon materials with a high fraction of sp~3 bonding recovered from compression of fullerene C60 under high pressure and high temperature,previously *** of photoluminescence and absorption spectra demonstrates that they are semiconducting with a bandgap range of 1.5-2.2 eV,comparable to that of widely used AM *** mechanical tests demonstrate that synthesized AM-Ⅲ carbon is the hardest and strongest AM material known to date,and can scratch diamond crystal and approach its *** produced AM carbon materials combine outstanding mechanical and electronic properties,and may potentially be used in photovoltaic applications that require ultrahigh strength and wear resistance.

关键词： amorphous carbon ultrahard ultrastrong semiconductor phase transition

Kinetics and mechanism of oxidation for nickel-containing pyrrhotite tailings

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International Journal of Minerals,metallurgy and materials 2021年第9期28卷 1469-1477页

作者： Alexander M.Klyushnikov Rosa I.Gulyaeva Evgeniy N.Selivanov Sergey M.Pikalov institute of metallurgy of the Ural branch of the Russian Academy of sciences Yekaterinburg 620016Russia

X-ray powder diffraction,scanning electron microscopy,energy dispersive spectroscopy,thermogravimetry,differential scanning calorimetry,and mass spectrometry have been used to study the products of nickel-containing pyrrhotite tailings oxidation by oxygen in the *** kinetic triplets of oxidation,namely,activation energy(E_(a)),pre-exponential factor(A),and reaction model(f(α))being a function of the conversion degree(α),were adjusted by regression *** case of a two-stage process representation,the first step proceeds under autocatalysis control and ends atα=*** kinetic triplet in the first step is E_(a)=262.2 kJ/mol,lg A=14.53 s^(−1),and f(α)=(1-α)^(4.11)(1+1.51×10^(-4)α).For the second step,the process is controlled by the two-dimensional diffusion of the reactants in the layer of oxidation *** kinetic triplet in the second step isЕa=215.0 kJ/mol,lg A=10.28 s^(−1),and f(α)=(-ln(1-α))^(-1).The obtained empirical formulae for the rate of pyrrhotite tailings oxidation reliably describe the macro-mechanism of the process and can be used to design automatization systems for roast-ing these materials.

关键词： pyrrhotite tailings oxidation thermogravimetry kinetics mechanism

Structure of low cobalt Fe-Cr-Co-based alloy for permanent magnets

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广东有色金属学报 2005年第2期15卷 314-317页

作者： Milyaev A.I . Korznikova G.F. Korznikov A.V. Kovneristii Ju.K. Yusupov V.S. A.A.baikov institute of metallurgy and materials Science ras Moscow119991 Russia institute of Problems of Superplasticity of Metals ras Ufa 450001 Russia

Results of an experimental research into evolution of structure and micro hardness hard magnetic alloy Fe-30Cr-8Co-0.7Ti-0.5V-0.7Si at complex two-level in isothermal conditions on the circuit deposit - torsion at various temperatures in single-phase ( are given. It is revealed that deformation results in transformation of coarse-grained structure in fine-grained in all volume of the sample, however the generated structure is non-uniform on section of a sample. In an active zone of deformation near to mobile it is brisk the microcrystalline layer with the size of grains about 5 microns which thickness poorly depends on temperature is formed. In process of removal from an active zone of deformation the size of grains is increased, and micro hardness decreases.

关键词：钴永磁材料合金硬度变形系数

Using new physics and technology to advance electrostimulated rolling of metals and alloys

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广东有色金属学报 2005年第2期15卷 530-532页

作者： Konstantin M. Kli mov Ivan I . Novikov baikov institute of metallurgy and materials Science Russian Academy of Sciences Moscow119991 Russia

Electrostimulated deformation of metals and alloys, using groove or smooth rolling, requires that several important conditions are satisfied. (1) The deformation site must geometrically overlap with the flow of electric current passing through a strip between the rolls; (2) The density of direct or alternating electric current supplied to deformation site must be sufficiently high (of an order of 104-106А/cm^2); (3) An efficient heat removal from the deformation site must be achieved. In general, the temperature of a strip must be within the range of 100-300℃. (4) The electric resistance at the roll-strip interface must be minimized. Our recent studies also indicate that the electrostimulated rolling in the shortcut regime is a further condition for obtaining high quality rolling of metals. In this regime, the rolls are placed in physical contact even in the absence of a strip that ensures an uninterrupted passage of electric current between the rolls.

关键词：金属材料合金物理性能轧制工艺