Features and mechanisms of the evolution of the structure-phase state of a quenched carbon steel under electrostimulated fatigue

Electron-microscopic examinations of the evolution of the defect substructure and phase composition have been carried out for quenched 60GS2 carbon steel subjected to multiple cycles of fatigue loading. The mechanisms by which the fatigue durability of the steel processed at an intermediate stage of loading by alternating electric current is increased have been investigated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 53–60, September, 2004.     

Influence of the surface anisotropy on the ground state of thin ferromagnetic films

A study is made of the ground state of a ferromagnetic film with a surface anisotropy which varies within wide limits from the easy-plane to the easy-axis type (– < 4) and with a bulk anisotropy of the easy-axis type ( 4). A rigorous analytic solution of the problem is given. The formulas obtained make it possible to calculate the distribution of the magnetization across the thickness of the film as a function of the parameters of the system. It is shown that there are two phase transitions from an inhomogeneous to a homogeneous state.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 71–76, July, 1980.The authors are grateful to B. A. Ivanov for his valuable comments and discussion of the results obtained.     

不锈钢表面激光熔覆层与喷焊层耐磨性对比研究

本文研究在１Ｃｒ１８Ｎｉ９Ｔｉ基体上采用激光熔覆和离子喷焊二种工艺形成的涂层对耐磨性的影响。使用５ｋＷ横流ＣＯ２激光器对预置在基体上的Ｃｏ基自熔合金粉末进行单道或多道扫描，得到的熔层与等离子焊层对比结果是：激光熔层缺陷率低，成品率高，其结构致密均匀，晶粒细小，成分稀释率更小，对基体热影响小，熔层硬度与强韧性更高。性能试验证明：激光熔层具有更高的抗擦伤磨损和抗冲击滑动高温磨损性能，耐磨性提高了一倍左右。     

Influence of chemical composition of filler's surface on the burning of foam plastics

The influence of additives such as TiO₂, Al₂O₃ and their mechanical mixture as well as aluminium oxide, the surface of which contains phosphorous and titanium-oxide nanostructures, on the combustibility of foam plast (trade mark PEN-I), produced on the basis of epoxide novolak block-copolymers, was studied. It was stated that the incorporation both phosphorous-containing and titanium-containing oxides in the composition results in significant (in two to five times) decreasing of the samples’ combustibility. The probable mechanism of inhibition of burning process for those combustion retarders was discussed.     

Nature of the stable oxide layer formed on an aluminum surface by work function measurements

The interaction of oxygen with clean aluminum results in formation of a stable oxide layer on the surface of the metal. This stable layer has a lower work function than that of clean aluminum. The nature of this stable layer is studied by measurement of work function changes. Heating of the stable layer, formed at room temperature and low oxygen pressures' (~10^?8 torr), in ultra-high vacuum resulted in a further decrease in the work function. The extent of this additional decrease was a function of temperature and the changes in work function caused by heating were irreversible in nature. At high oxygen pressures (p_O2 > 10^?2 torr) the effect of growth of incorporated oxide on the net limiting work function change appears to be small and the reversible changes in the work function are mainly a result of the variation in the amount of surface oxide. At 250°C, the contribution of incorporated oxide to net limiting work function change was dependent on oxygen pressure when it was formed at low oxygen pressures (P < 10^?7 torr). However, when the incorporated oxide was formed at oxygen pressures above 10^?7 torr, its contribution to the limiting work function change and, perhaps, the structure of the incorporated oxide itself were nearly independent of oxygen pressure. The difference in limiting work function change at various oxygen pressures was mainly because of the difference in the limiting amounts of surface oxide. Similar behavior is expected at room temperature.     

Influence of a strong electric field on the decay of autoionizing states formed when multiply charged ions approach a metal surface

Upon collisions of multiply charged ions with a surface, the electric field of the image charge causes Stark splitting of the ion levels; in this case, the Stark states whose energy approaches the electron binding energy in the metal with a decrease in the distance to the surface are selectively occupied. It is shown that consideration of the electric field effect leads to an increase in the probability of Auger transitions in the presence of field. This effect changes our representations about the scheme of occupation of lower levels of multiply charged ions.     

Influence of the bilayer thickness of nanostructured multilayer MoN/CrN coating on its microstructure,hardness, and elemental composition

Multilayer nanostructured coatings consisting of alternating MoN and CrN layers were obtained by vacuum cathode evaporation under various conditions of deposition. The transition from micron sizes of bilayers to the nanometer scale in the coatings under investigation leads to an increase in hardness from 15 to 35.5 GPa (with a layer thickness of about 35 nm). At the same time, when the number of bilayers in the coating decreases, the average Vickers hardness increases from 1267 HV_0.05 to 3307 HV_0.05. An increase in the value of the potential supplied to the substrate from–20 to–150 V leads to the formation of growth textures in coating layers with the [100] axis, and to an increase in the intensity of reflections with increasing bilayer thickness. Elemental analysis carried out with the help of Rutherford backscattering, secondary ion mass spectrometry and energy dispersion spectra showed a good separation of the MoN and CrN layers near the surface of the coatings.     

Influence of smoking on the elemental composition of oral fluids: a TXRF approach

This work presents a study of elemental composition (major, minor and trace elements) of oral fluids such as saliva and gingival crevice fluid, and their relation with smoking. Spectrochemical analyses were accomplished by the total reflection X‐ray fluorescence (TXRF) method using synchrotron radiation. Smoking habit is a well‐known factor of risk that can trigger the development of periodontal diseases. The presence of certain elements and their correlation with smoking could be used to predict the development of oral affections, i.e. gingivitis. Two set of patients, smokers and non‐smokers, were selected according to certain criteria to analyze saliva and gingival crevice fluid. The elemental concentrations were measured, and the differences between their mean values of both groups were determined. The results reveal significant differences in the elemental concentrations of saliva. On the other hand, the mean values of elemental concentrations in gingival crevice fluid show fewer differences between both groups. The most significant differences in concentration between smokers and non‐smokers were found in saliva samples for S, K and Ca. In addition, a significant difference in the concentration of Cl in gingival crevice fluid was observed between both groups. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of an intermediate layer with space-dependent permittivity on the ground state energy of an electron in a spherical complex nanoheterosystem

The effect of the interfaces of a multilayer spherical microcrystal on a charged particle is investigated. The case is considered where an intermediate layer with space-dependent permittivity exists near the interfaces. The dependence of the potential energy of the charged particle on distance is established by the method of the classical Green’s functions. For the example of an HgS/CdS spherical structure, the energy of the ground and excited states of an electron is calculated both in the presence of an intermediate layer with space-dependent permittivity and in its absence.     

Influence of surface electric fields on the alignment of the hydrogen-2p state after beam-foil-excitation

In contrast to other atomic systems, foil excited hydrogen or hydrogen-like atoms show a negative alignment for various energy ranges. We suggest that this particular behaviour results from the degeneracy of differentL states in hydrogenic systems and an observable influence of a surface electric field modifying the initial alignment via Stark effect.     

Influence of geographic populations on the elemental composition of pine phytomass and soil

In the long-term (30 years) field provenance experiment (Novosibirsk, Russia) with Scotch pine Pinus sylvestris L. from different geographical populations, X-ray fluorescence analysis with synchrotron radiation (XRFSRA) was used to estimate the concentration of 16 chemical elements in different components of the phytomass collected from living trees and the soil under them. The statistically significant influence of the “geographical population” factor on the elemental composition of different components of phytomass and soil was shown. A relationship between chemical properties and morphometric traits was found.     

Influence of an interface double electric layer on the superconducting proximity effect in ferromagnetic metals

The electric field within the double electric layer that occurs when two conductors with different work functions come into contact induces interface spin-orbit coupling. In the case of contact of a conventional, s-wave superconductor with a ferromagnetic metal, the coupling is predicted to give rise to the appearance of triplet superconductivity on both sides of the interface. The form of the triplet component of the condensation amplitude is determined, and the ability of the triplet superconductivity to penetrate into the ferromagnet on the usual coherence length is shown.     

古代玻璃样品表面因素对便携式X射线荧光定量分析的影响

便携式X射线荧光光谱分析技术(PXRF)是一种表面分析技术,样品表面状况对定量分析结果有很大的影响.本文采用PXRF对新疆、广西、江苏等地出土的Na2O-CaO-SiO2,K2O-SiO2和PbO-BaO-SiO2体系古代玻璃的风化表面与内部进行了定量分析,指出了主要助熔剂的含量在不同部位的变化.另外,还研究了样品与参...     

The effect of nanostructured surface layer on the fatigue behaviors of a carbon steel

A nanostructured surface layer was formed on a carbon steel by means of surface mechanical attrition treatment (SMAT). The microstructure of the surface layer of the SMATed sample was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness and residual stress distribution along the depth from the SMATed surface layer were measured at the same time. Fatigue behaviors of the carbon steel subjected to the SMAT process were investigated. A nanostructured layer with average grains size of ∼12.7 nm was formed, of which microhardness is more than twice as high as that in matrix and residual compressive stress can reach about −400 MPa with maximum depth of ∼600 μm. The fatigue strength of as-received sample is 267 MPa and that of SMATed sample is 302 MPa based on fatigue life 5 × 10⁶ cycles. The SMAT process has improved the fatigue strength by as much as 13.1% for the carbon steel. It is shown that the SMAT is an effective method to render the material with the features, such as a nanostructured and work-hardened surface layer as well as compressive residual stresses, which can pronouncedly improve the fatigue strength of the carbon steel.     

The recoilless fraction of the oxide surface layer formed on small iron particles

Small iron particles with oxide surface layer were studied by Mössbauer Spectroscopy at various temperatures in the range of 5K to 300K. The Debye temperature of the oxide layer and the temperature dependence of f2/f1 were obtained, where f1 and f2 are the recoilless fractions for the inner α-iron core and the oxide layer respectively. Furthermore, the method of estimating the thickness of the oxide layer was improved.     

Method for modifying the structure and elemental composition of the solid surface during a high-voltage vacuum discharge

A new method for modifying the surface of a solid, which makes it possible to change effectively the structure and elemental composition of the surface with a high precision, is developed and tested experimentally. The method is based on the action of the plasma of a pulsed high-voltage vacuum discharge, the ion beam from the plasma, and the electron beam on a solid target. The emission and plasma parameters are observed in a pulsed electric field produced in the diode system to which a pulsed voltage with an amplitude of ～10³–10⁵ V and a duration from 10^?9 to 10^?5 s is applied.     

Structural properties and current transport in a nanocomposite formed on a silicon surface by oxidation of the porous layer

The possibility of obtaining a Si-SiO₂ nanocomposite layer by oxidation of porous silicon is demonstrated. The nanocomposite thus prepared consists of silicon oxide with inclusions of crystalline silicon in the form of rounded particles 5 to 30 nm in diameter and a filamentary cellular structure with filaments a few nanometers thick. The I-V characteristics of these structures were measured under different sample excitation conditions (photo-and thermal stimulation). The trap concentration and effective carrier mobility are estimated. Carriers are found to be captured intensely by traps created in the large-area interface in the composite structure.     

Frequency shift in the system formed by a metastable helium atom and a lithium atom in the ground state

The cross sections of magnetic resonance frequency shifts are calculated for the first time in the system formed by a metastable helium atom and a lithium atom in the ground state. The results are compared with the results of calculations for He-K systems. It is shown that the shift cross section increases upon heating from 50 to 550 K, changing its sign near T = 80 K.