Vol 8, No 4 (2017)

Meso- and nanoscale structural polymorphism of monolayer J-aggregates of four cyanine dyes are investigated. Three mesoscale morphological types are observed: ribbons, rhombic leaves, and tubes. Tubes are formed during cylindrical spinning of ribbons. Lined substructure characterized by the line width of about 7 nm is found in the case of monolayers of monomethine cyanine dyes at the nanoscale.

This article describes the application of the generalized Pascal triangle for description of fixed variation of the oscillation amplitude of friction force upon frictional interaction of materials, and the region of interest in terms of friction theory and material wear is highlighted. Mathematical models of friction are presented, and their efficiency is confirmed by experimental data.

Methods of modern material physics were used for the formation and evolution of the structural and phase state during electron-beam treatment and multiple-cycle fatigue in 20Cr23Ni18 stainless steel. Patterns of the structure, phase composition, and defective substructure of 20Cr23Ni18 austenite steel at the multicycle failure load were determined as well as the gradient character of evolution of the structural and phase states and defective substructure of steel irradiated by electron beams under different conditions.

The influence of hydrogen embrittlement of the aluminum Al–4%Cu–0.2%Mg alloy on the parameters of localized plastic strain is studied. Digital speckle photography is used to visualize the localized strain patterns in the D1 alloy. The velocity of localized deformation bands as a function of the yield strength for nonhydrogenated and hydrogenated samples is found.

Intermetallic alloys in the Ni–Al system strengthened through inclusions of molybdenum and tungsten borides by means of sequential exothermic reactions in a two-layer charge are fabricated. NiAl and Ni₂Al₃ intermetallic phases and molybdenum (Mo₂B₅) and tungsten (W₂B₅) borides are identified in alloys by the methods of X-ray diffraction and elemental analysis. It is established that Mo₂B₅ and W₂B₅ inclusions are characterized by high values of microhardness (Mo₂B₅—24.4 GPa and W₂B₅—29.2 GPa).

The investigation is focused on the study of the structure, fracture, and phase composition of standard industrial pseudo-alpha-titanium alloy and the same titanium alloy alloyed with ruthenium. Also, the possibility to increase the low-cycle fatigue and resistance to stress corrosion cracking of industrial titanium allow using cathodic alloying with ruthenium.

Resistance to high cycle fatigue (HCF) at room temperature and operating temperatures of the VKS-180 high-resistance steel was studied. It was found that at room temperature the test results should be schematized by a fatigue curve with inclined left and horizontal right linear segments; and at 400°C, with one linear segment. A method of determination was proposed for each case and the HCF characteristics were calculated. The related character of the fatigue failure was observed at 20 and 400°C.

Using the Rietveld X-ray method, the powders of tricalcium phosphate (α-TCP) were analyzed after their treatment in a planetary mill in various liquids (butanol, isobutyl alcohol, acetone, and ethanol). No features of the decomposition of α-TCP were detected and the parameters of its atomic-crystal structure did not change significantly. The reduction of the coherent scattering domains (DS) (d ~ 800 Å) was a major contribution to X-ray line broadening, while its value did not depend on physical properties of liquids. Particles dispersed during their processing in the mill owing to their brittle destruction by chipping. After 60 min of powder processing in butanol, mean particle size decreased by a factor of five (from 9.7 to 2 μm). After annealing at 1300°C, the fluorohydroxyapatite phase was detected in powders, whose formation was assisted by the impurities from fluorine-containing structural elements of the mill.

Analysis of the phase composition, microstructure, and mechanical properties of the semifinished materials made of the pseudo-β alloy of VT22 grade after strengthening thermal treatment in different modes was carried out. Evaluation of the corrosion and mechanical strength of the semifinished materials made of the VT22 alloy was performed. Recommendations on selection of the strengthening thermal treatment mode providing the optimum set of properties were given.

The technique for the preparation of composite materials in which ice serves as the matrix and polymer fillers (the reinforcement) with various chemical compositions and morphologies and chemical ice modifiers serve as the tool for affecting its structure and properties is proposed in this work. The physical and mechanical properties of the composites (bending strength) are studied, and the character of the effect of two-dimensional and three-dimensional polymer networks, their amount, assembling, and concentration of modifiers are revealed. Also, the simultaneous action of polymer fillers and modifiers is considered. It is shown that the proposed technique makes it possible to control the physical and mechanical properties of composites on the basis of ice and create substantially stronger materials when compared to natural ice.

The results of the research works on the development, study, and approbation of promising heatresistant REE-containing intermetallic alloys based on ortho- and gamma-titanium aluminides (Ti2AlNb, TiAl) performed at the All-Russian Scientific Research Institute of Aviation Materials (VIAM) for solving the current problems of aircraft engine construction within the implementation of the complex scientific direction 7.1 “Intermetallic Alloys Based on Titanium” (“Strategic Directions of the Development of Materials and Technologies of Their Processing for the Period until 2030”) [1] are presented. The energy-efficient technological regimes of vacuum arc melting of ingots made of ortho and gamma alloys and having a homogeneous chemical composition and structure are developed; it is shown that the introduction of gadolinium microadditives in the amount of 0.05–0.2 at % into the studied alloys gives a significant modifying effect and forms a finely lamellar structure in ingots, which is favorable from the point of view of the combination of heat-resistant and performance properties. The structural changes and the combination of mechanical characteristics of new VIT5 ortho alloy depending on the heat treatment regimes are studied.