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The present work was aimed at the investigation of effect of High Energy Ball Milling (HEBM) time on the sintering kinetics, structure, and properties of heavy tungsten alloy (HTA) W-7%Ni-3%Fe. The HTA samples were obtained from the nanopowders (20-80 nm) by conventional liquid phase sintering (LPS) in hydrogen and by Spark Plasma Sintering (SPS) in vacuum. The HTA density was shown to depend on the HEBM time non-monotonously that originates from the formation of non-equilibrium solid solutions in the W-Ni-Fe systems during HEBM. The SPS kinetics of the HTA nanopowders was shown to have a two-stage character, the intensity of which depends on the Coble diffusion creep rate and on the intensity of diffusion of the tungsten atoms in the crystal lattice of the -phase. The kinetics of sintering of the initial submicron powders have a single-stage character originating from the intensity of the grain boundary diffusion in the -phase. The dependencies of the hardness and of the yield strength on the grain sizes were found to obey the Hall-Petch relation. The hardness, strength, and dynamic strength in the compression tests of the fine-grained tungsten alloys obtained by SPS and LPS were studied.

A diffusion welding of coarse-grained and ultrafine-grained (UFG) specimens of titanium near-α alloy Ti-5Al-2V used in nuclear power engineering was made by Spark Plasma Sintering. The failure of the welded specimens in the conditions of hot salt corrosion and of electrochemical corrosion were shown to have preferentially intercrystalline character. In the case of presence of macrodefects, crevice corrosion of the welded joints was observed. The resistance of the alloys against the intercrystalline corrosion was found to be determined by the concentration of vanadium at the titanium grain boundaries, by the size and volume fraction of the β-phase particles and by the presence of micro- and macropores in the welded joints. The specimens of the welded joints of the UFG alloy have higher hardness, hot salt corrosion resistance and the electrochemical corrosion.

The anisotropy of the properties of a ceramic cutting insert (for three faces) obtained by the lithography-based technology from the Al2O3 + ZrO2 composite has been studied. The study was carried out using the indentation method and Mayer’s law. This method, in contrast to the bending test, excludes the sample destruction. All the studies were carried out on three faces of a ceramic cutting insert made of a composite Al2O3 + ZrO2. The behavior of the Mayer index was studied in the range of loads from 2 to 20 kg and from 0.2 to 1 kg. The results of studying the density, phase composition and microstructure of each face of the sample are presented. The study of the adhesion of the printed layers were also carried out using a Knoop indenter. No anisotropy of the hardness was observed in the load range up to 10 kg. It is shown that a layered structure present in the sample, contributes to the hardness anisotropy under the load of 20 kg and more. No anisotropy of the fracture toughness is observed in the load range of 2 – 20 kg. The results of using a Knoop indenter revealed a high adhesion between 3D printed layers. Studies using a Knoop indenter have indicated high adhesion between the layers of 3D printing.

AlMgB14-based materials have been synthesized by spark plasma sintering of an Al12Mg17–B powder mixture at 1300 and 1400°C. The phase composition, structure, and properties of these materials have been studied. According to X-ray powder diffraction evidence, spark plasma sintering leads to the formation of the AlMgB14 phase and the MgAl2O4 spinel. The content of the AlMgB14 phase in the materials is ~95 wt %. At a sintering temperature of 1400°C, the resulting material has a hardness and relative density of 30.1 GPa and 99.3%, respectively. It has been demonstrated that a major source of oxygen in the powder mixture is a B2O3 oxide film on the boron powder surface. Thus, when the Al12Mg17 intermetallic powder is used as a precursor, the reaction of AlxMgy intermetallic compounds with B2O3 leads to the formation of the MgAl2O4 spinel.

We have synthesized Na1 ¿ xZr2(PO4)3 ¿ x(¿O4)x and ¿a0.5 ¿ xZr2(PO4)3 ¿ x(¿O4)x (X = Mo, W; 0 ¿ x ¿ 0.5) compounds with the NZP structure. Their thermal expansion has been studied in the temperature range 25¿800°C using high-temperature X-ray diffraction and shown to have a tendency to decrease as the occupancy of the extraframework sites in their structure decreases. Ceramic samples with a relative density above 97.5% have been prepared from the synthesized phosphate molybdates and phosphate tungstates by spark plasma sintering. Their strength characteristics (microhardness and fracture toughness) have been determined and they have been characterized by hydrolytic stability tests.

In this work, AlMgB14–TiB2 composite materials were obtained by thermochemical-coupled self-propagating high-temperature synthesis (SHS) and subsequent spark plasma sintering. The mechanism was proposed for the formation of the composite materials in the thermochemical-coupled SHS mode. The phase composition, microstructure, and properties (density and Vickers hardness) of the dense AlMgB14–TiB2 materials were investigated. At a sintering temperature of 1470 °C, AlMgB14 is decomposed into AlB12 and Mg. The sample sintered at 1470 °C with a holding time of 5 min had a maximum average hardness of 32.1 GPa.

Investigations of plastic deformation of fine-grained ceramics based on alumina obtained by the method of spark plasma sintering in the temperature range of 1150-1320 ° C at an applied stress of 40-100 MPa are presented. Based on the experimental data, the parameters of rheological equations were established. It is shown that the mechanism of high-temperature deformation of alumina is superplasticity. In the process of plastic deformation, the grains of alumina do not stretch, which confirms the mechanism of superplasticity - grain boundary sliding. The activation energy for superplastic deformation was Q = 17.8 kTm at d = 6 μm and Q = 24.6 kTm at d = 1 μ m, which is very close to the activation energy of grain boundary diffusion in aluminum oxide Qb = 20 kTm. For a coarse-grained material, an assumption was made about a possible mechanism for lowering the activation energy due to the generation of dislocations by the grain boundary.

We have studied the sintering kinetics of Al2O3–ZrO2–Ti(C,N) powders during hot pressing and spark plasma sintering. The results demonstrate that, at slow heating rates and under identical hot pressing and spark plasma sintering conditions, the consolidation processes have identical kinetics in the active densification stage and are characterized by identical activation energies.

A comparative study was made of the kinetics of the sintering of Al2O3/ZrO2/Ti(C,N) powders under hot pressing and spark plasma sintering conditions. It was found that the consolidation processes under identical hot pressing and spark plasma sintering conditions at low heating rates at the intense densification stage are characterized by identical kinetics and have equal activation energies.