Structural Features and Distribution of Silicon in Ferrosilicon-Magnesium Modifiers

It is noted that the technology for the manufacture of ferrosilicon-magnesium modifiers (crystallization into an ingot in a mold or into a chip on a water-cooled drum) forms their quantitative and qualitative structural differences: the size and distribution of phases, the scatter of the content of elements, etc. The fundamental differences are shown and the features of the distribution of silicon as a base element in ingot and chip modifiers are described. It was found that in ingot modifiers the vast majority of silicon-containing phases are ξ(FeSi) and ζ' (FeSi2), and with a significantly lower content of pure silicon particles and phases, these are α1(Fe3Si) and α2(Fe2Si). The picture of the phase structure of the modifier chip has been determined. In it, the 1st mode corresponds to the presence of a set of phases α1(Fe3Si) and α2(Fe2Si), and the 2nd mode, as well as in the ingot modifiers ξ (FeSi) and ζ'(FeSi2), but is shifted to the lower boundary of the region their existence. Particles of pure silicon are completely absent in the chip modifier.

ACHROMATIZATION OF THE VOLUME HOLOGRAPHIC OPTICAL ELEMENS

The work considers a two-component holographic optical system having a base element in the form of a thick (volume) hologram optical element and intended for use in a given spectral range. The calculation of a two-component holographic system is carried out using formulas obtained from the mirror-lens model of the thick hologram element proposed by the author. It is indicated that according to the mirror model a thick hologram optical element is achromatic in a first approximation. For this the local period of the volume diffraction structure of the hologram element must be many times greater than the working wavelength, and the transverse dimensions of the element must be less than its thickness. Analytical expressions are given for the mutual correction of the chromatic aberration of the position of a thick hologram optical element and a relief kinoform element. The condition for achromatization of this two-component holographic system is formulated.

Thermal Expansion and Microstructure Behavior at Elevated Temperature of various {Ni, Co}-based Cast Superalloys

This paper aims to investigate the thermal expansion behavior, up to an elevated temperature, of superalloys based on nickel and cobalt with various proportions and designed to be strengthened by tantalum carbides. The as-cast microstructures of these superalloys and their evolutions at two very high temperatures were also of interest. All results are discussed by considering the Ni/Co repartition in the base element position. It appears that when the Ni content is higher than the Co one: 1/the thermal expansion is slower, 2/the as-cast microstructures as well as the ones stabilized at high temperature contain not only TaC but also chromium carbides, and 3/the hardness in as-cast or aged state is lower.

Influence of the Base Element on the Thermal Properties of Non- Ferrous Chromium-Rich TaC-Containing Alloys Elaborated by Conventional Casting: Part 3: Surface and Cross-Sectional Metallographic Characterization of the Oxidized Alloys

The six alloys the thermal properties of which and the tendency to oxide spallation of which were studied in the first two parts of this work, were here characterized after oxidation for 70 hours at 1250°C. The external chromia scale, and also the CrTaO4 subsurface oxide, formed for all the alloys, almost independently of the Co and Ni proportions in the base element content. But, because of the formation of more CrTaO4 for the nickel-richest alloys probably due to the higher availability of Ta in the matrix and its easier diffusion towards the neighbourhood of the oxidation front, the adherence of chromia was weakened and spallation, suggested by the thermogravimetric curves in the second part of this work, is here really observed and the denuded part of alloys clearly seen. The degradation of the subsurface, which can be in a first time summarized by the development of a carbide-free zone and a {Cr, Ta}-depleted zone, depends on the Co and Ni proportions. The microstructure of the bulk is differently affected by long exposure at elevated temperature. The changes in carbide population characteristics are stronger for the nickel-based alloys than for the cobalt-based ones. Finally, the isothermal oxidation behaviour is best for the nickel-richest alloys but the oxide spallation behaviour and the potential mechanical properties are the best for the cobalt-richest alloys.

MODEL OF CALCULATING DIFFICULTY OF NEW GENERATION OPTICAL COMMUTATION SYSTEMS

The article presents the analysis of various circuits of the multistage switching systems and their main characteristics. The model of calculating the complexity of the new generation optical switching systems based on 4x4 switches has been developed. These switching systems have a new property, which no one multi-stage scheme possesses: the strict non-blocking capacity with parallel data transfer and arbitrary packet swapping. There has been compared the difficulty of the proposed systems, such as the switching difficulty of the base element and the diameter with well-known multi-stage schemes. The analysis showed that the optical switching systems of the new generation have an advantage - a fewer number of cascades.

Influence of the M and M’ Metals on the Carbides Population in As-Cast M’-based Alloys Designed to be MC-Strengthened

High temperature applications such as turbine blades for aeronautics or molten glass-shaping tools require the use of refractory metallic materials. Among the later ones, cast superalloys based on some transition metals and reinforced by MC carbides stay in good place and their metallurgy merits to be well known. This work consists in a general exploration of the as-cast microstructures which can be obtained after solidification and solid state cooling down to ambient temperature for a wide series of alloys for which the base element and the MC-former element both vary. For fixed contents in chromium and carbon contents, the compositions of a total of nineteen alloys were considered. These alloys are based on Ni, Co, Fe or Nb and the M content was each time chosen to favor the appearance of TiC, TaC, NbC, HfC or ZrC, as single carbide in a given alloy. After elaboration, metallographic samples were observed by electron microscopy to investigate the obtained microstructures. The obtained results show first that the MC carbides were in many cases successfully obtained at the expense of other possible carbides (for all Co-based alloys for example) but there are also several exceptions (notably for some Ni-based alloys). Second, the obtained monocarbides have a eutectic origin and they are script-liked shaped. However they are here too some exceptions, as the rare HfC obtained in a Nb-base). In general, the results obtained in this work show that the principle of dendritic matrix combined with MC carbides with a script-like morphology is not necessarily obtained: the nature of the {base element, MC-former element} combination governs the microstructure of the alloy in its as-cast state for these particular compositions in chromium and carbon. In some cases other carbides may appear and the microstructures may be even of another type.

Deterministic Irreversibility and The Matter Structure

The role of existence of the deterministic irreversibility mechanism in development of evolution physics is studied. The short explanation of physical essence of this mechanism is offered. Based on this mechanism, is proved, that the base element of matter should be an open non-equilibrium dynamic system (ONDS). The principles of the emergence, existence and development of the ONDS hierarchical structure are considered. The questions about hierarchy of the matter and existence of stationary states ONDS are studied. The question, how external constraints determine of the evolution of ONDS, is analyzed. Equations that determine the development of ONDS are submitted.

Behavior of Cast {TI OR TA}-Containing Alloys Based on Nickel and/or Cobalt in High Temperature Oxidation:Effect of the NI/ CO Ratio

Many of the cast superalloys chosen for specific applications at high temperatures, such as tools devoted for shaping molten glass, are based on nickel or cobalt. They contain chromium and carbon to achieve good resistances against both mechanical stresses and hot oxidation/corrosion, by favoring the formation of reinforcing carbides at solidification and the development of a protective oxide scale of chromia during service. In presence of tantalum or titanium in the chemical composition of the alloys, high performance MC carbides may be obtained but this depends on the base element. One recently observed how the respective proportions of nickel, cobalt and chromium may promote the formation of TiC or TaC at the expense of chromium carbides. The ratings chosen for No, Co and Cr may have high influence on the oxidation of the alloys at high temperature this is what was studied in this work.

New 2D graphene hybrid composites as an effective base element of optical nanodevices

For the first time, we estimated perspectives for using a new 2D carbon nanotube (CNT)–graphene hybrid nanocomposite as a base element of a new generation o optical nanodevices. The 2D CNT–graphene hybrid nanocomposite was modelled by two graphene monolayers between which single-walled CNTs with different diameters were regularly arranged at different distances from each other. Spectra of the real and imaginary parts of the diagonal elements of the surface conductivity tensor for four topological models of the hybrid nanocomposite have been obtained. The absorption coefficient for p-polarized and s-polarized radiation was calculated for different topological models of the hybrid nanocomposite. It was found that the characteristic peaks with high intensity appear in the UV region at wavelengths from 150 to 350 nm (related to graphene) and in the optical range from 380 to 740 nm irrespective of the diameter of the tubes and the distance between them. For waves corresponding to the most intense peaks, the absorption coefficient as a function of the angle of incidence was calculated. It was shown that the optical properties of the hybrid nanocomposite were approximately equal for both metallic and semiconductor nanotubes.