Roman Osaulenko

• Petrozavodsk State University

Formation mechanism and crystallization kinetics were studied in series of rapidly solidified metallic glasses Fe80-xCoxP14B6 with x = 23, 25, 28, 32, 35 and 40 at.%. As soft magnetic materials, they surpass characteristics of commercial Iron-Nickel Metglas® 2826 alloy: differential permeability of as quenched amorphous ribbons is of about 110000,...

The nitriding of the oxide compounds Ta 2 O 5 , Nb 2 O 5 , Mg 4 Та 2 O 9 и Mg 4 Nb 2 O 9 was carried out in two stages: 1 — reduction of oxides at the residual pressure of nitrogen or argon in the reactor of 5-10 kPa and a temperature of 820°C for 4 hours; 2 — nitriding of the obtained products in a nitrogen atmosphere at an overpressure of 30-100...

The mesoporous structure of niobium powders of specific surface areas from 32 to 150 m²/g obtained through reduction of niobium-oxide compounds by magnesium vapors has been investigated. A doubling of the specific surface area of magnesium-thermic niobium powders in comparison to tantalum powders has been shown to be caused by the larger volume and...

We have studied the effects of the specific surface area of mesoporous magnesiothermic niobium powders and ammonolysis conditions on characteristics of the reaction products. Ammonolysis was carried out in the temperature range 400–800°C using powders with specific surface areas of 18, 83, and 123 m²/g. The results demonstrate that the ammonolysis...

We report about formation mechanism, crystallization kinetics and magnetic properties observed in the series of rapidly solidified F e80−xCoxP14B6 metallic glasses with x = 25, 32, 35 and 40 at.%. Magnetic soft F e80−xCoxP14B6 metallic glasses have 15–25 µm thick and 2–8 mm wide. The ribbon samples were created to meltspun onto the massive copper w...

We have studied the effect of specific surface area and reaction product leaching conditions on the crystal structure of mesoporous tantalum powders prepared by reducing tantalum oxide compounds with magnesium vapor.

Tantalum nitrides are synthesized by ammonolysis of a mesoporous magnesiothermic tantalum powders. The effect of specific surface area of the powders and synthesis temperature on product composition is shown. Nitrogen content in the ammonolysis product of tantalum powder with a specific surface area of 56 m² g–1 corresponds to oxynitride TaON expos...

Crystallization kinetics and magnetic properties were studied in series of rapidly solidified metallic glasses Fe80-ξCoξP14B6 with ξ = 25, 32, 35 and 40 at. %. Differential scanning calorimetry (DSC) was employed to determine crystallization temperature and to demonstrate the incubation phenomenon at isothermal annealing. Fitting DSC traces recorde...

The composition, structure, and morphology of compounds formed in an argon arc discharge with a graphite cathode and a composite anode are studied by the methods of Raman scattering, X-ray diffraction analysis, X-ray microanalysis, and electron microscopy. Among the synthesis produces, graphite-like substances and metal carbides dominate; metal mic...

This paper presents a study of arc discharge sputtering products obtained with metal-graphite anodes. The sputtering products are shown to contain carbides of all the metals studied, except for nickel and copper carbides. Most of the sputtering products contain spheroidal metal or carbide particles, fullerenes, nanotubes, and filaments up to 2 μm i...

This paper examines the effect of sodiothermic reduction conditions on the crystal structure of tantalum and the structural changes induced by subsequent modification of the tantalum powder.

A method of synthesis of iron, silicon, titanium, and tungsten carbides in an argon arc between graphite electrodes is developed. It is found that iron, silicon, and titanium atoms introduced into the interelectrode gap cause the voltage drop across the gap to decrease, whereas tungsten atoms increase this voltage. The X-ray diffraction analysis of...

The crystal structure, morphology, and elemental composition of evaporation products of argon arc discharge on graphite electrodes containing vanadium have been studied. It is shown that vanadium carbide V8C7 synthesized under these conditions enters the compositions of both the sputtering products formed on the walls of discharge chamber and outgr...

The crystal structure of the perovskite rhombohedral modification before and after mechanoactivation in air and in carbon dioxide is studied using the X-ray diffraction method. It is shown that a medium in which an as-grown perovskite crystal is milled influences the degree of its amorphization but does not influence either the size of ordered area...

217 Functional materials containing ferroelectric crystals of metatitanates of divalent metals (barium, strontium, lead) are promising for manufacturing optical and piezo ceramics, ceramic memory elements, and artificial photon structures with energy gaps [1‐6]. To obtain such materials, it is necessary to have single-phase ferroelectrics with stoi...

Diffuse scattering on the X-ray diffraction pattern of fullerite C60 is analyzed. The characteristics of the short-range order of the amorphous component of fullerite are determined by the Finbak-Warren method. It is established that the short-range order of the amorphous component is similar to the short-range order of lonsdaleite.

The short-range order and microinhomogeneity structure of laboratory samples of glasses belonging to the diopside-orthoclase-apatite system with different percentages of components were investigated by X-ray diffraction and small-angle scattering. A correlation between a change in the chemical composition of a glass, causing its segregation, and th...

The short-range order of multicomponent glasses in the diopside–orthoclase–apatite system with different contents of the initial components is investigated by X-ray diffraction upon heat treatments at different temperatures. It is found that the short-range order parameters change considerably when the apatite content in the melt exceeds 20 wt %. I...