Some Yu.G. Dorofeev’s memoirs about joint work and meetings with outstanding materials science expert G.V. Samsonov are given. Meetings in Yugoslavia were of particular importance where G.V. Samsonov and M.M. Ristićtogether with other worldfamous scientists created the International Institute for the Science of Sintering. In the last years of his life, G.V. Samsonov proposed the concept of sintering activation by additives that act as electron acceptors and additionally contribute to the ionic bond in the matrix material. The paper considers the possibility of using this concept in the development of activating additives that reduce the activation energy of the plastic deformation of iron-based powder materials. Sintering activation when forming stable electronic configurations can be accomplished by: 1) accelerating the grain-boundary heterodiffusion of the matrix material in the presence of phase segregations containing an activating microadditive (W–Ni system); 2) intensifying shrinkage durng the plastic flow of matrix material particles facilitated by diffusion porosity formed in the additive particles as a result of predominant additive atom diffusion into base metal particles (Fe–Ni, Fe–Co, Fe–Mn systems); 3) increasing the self-diffusion coefficient of base metal atoms due to the expanded area of a less close-packed crystal lattice (αphase) upon activating additive dissolution (Fe–Mo system). The article reviews the information available on the prospects for using manganese and chromium as compaction activating additives. The compaction activation energy of iron-based powder materials can be reduced by introducing manganese additives. At the same time, the use of diffusion saturation technology is promising. The question of using chromium as an activator does not have an unambiguous answer and suggests the need for further study.

The combination of alloying elements in the form of a masteralloy (MA) powder gives the possibility to protect oxygen-sensitive elements against oxidation and to promote the formation of a liquid phase that enhances the sintering mechanisms. As compared to the prealloying approach, the MA route has lower impact on compressibility and provides more flexibility in the selection ofthe final composition. Knowledge of the chemical aspects of sintering combined with the possibility to tailor the properties of sintered steels through the use of specific MA compositions and with the development of novel atomizing methods to produce MA powders may, in the near future, position the MA approach as a very interesting alternative to conventional alloying methods. In this work, sintered steels containing cost-effective Fe–Mn–Si masteralloysare processed at increasing temperatures in the range between 1120 and 1300 °C. The combination with different base powders provides a good overview of the properties that can be obtained with this alloying approach. Besides, the evaluation of microstructure and mechanical properties as a function of temperature allow understanding the real benefits of increasing the sintering temperature, in order to find an appropriate balance between the economic requirements and the material performance.

Major research challenges in the field of solid-state sintering are noted following the authors’ recent paper (J. Am. Ceram. Soc. 2017. Vol. 100. P. 2314–2352). They are highlighted in the areas of (i) modeling and simulation (mesoscale as well as macroscale), (ii) microstructural evolution with respect to interface structure, (iii) novel sintering techniques, and (iv) solutions for practical systems.

The forecast of maximum stresses on compaction tools is frequently based on the so-called compressibility curves, obtained according to specific standards. The analysis of compressibility curves enables to draw a simple analytical law, to utilize for further developments. The relationship between radial and axial pressure is described. The radial pressure is the design datum for the correct dimensioning of dies. Literature data on the relationship between applied pressure and friction coefficient enables to derive a model linking compact geometry and axial pressures effectively needed to reach specific densities. For part shapes characterized by a discrete extension on height – such as bushings, for instance – the effects of geometry are linked to 2 dimensionless parameters, one of physical nature (product of the pressure ratio multiplied by friction coefficient) and one of geometrical nature (ratio between «vertical» friction surfaces and double of compaction area). These dimensionless parameters enable to draw the «real» compressibility curves, linked to specific geometries. For part shapes characterized by small height – such as thin disks or plates – the effects of geometry again depend on two dimensionless parameters: one of physical nature (ratio between two times the friction coefficient and pressure ratio) and one of geometrical nature (ratio radius/height of the thin disk). Thinner the disk, higher the pressure needed to attain a given density. The theoretical results are compared with experimental data. The agreement between experimental data and forecasts based onthe theoretical approach is good. The study proves that the standard compressibility curves, if uncritically utilized for predicting stresses acting on tools, are unsuitable to predict the stresses really acting at compaction end.

The paper reviews the results of using the process of self-propagating high-temperature synthesis (SHS) to obtain high-temperature nickel alloys and composites based on titanium carbide (TiC) and nickel. In order to reduce the brittleness of these composites, it was proposed to replace the TiC ceramic phase by the MAX phase of titanium silicon carbide (Ti₃SiC₂ ) and use the SHS process to obtain a Ti₃SiC₂ –Ni skeleton composite. Nickel for Ti₃SiC₂ skeleton infiltration was introduced in three variants: by introducing to the reaction mixture; in the form of a briquette located between two SHS charge briquettes; and similar to the second variant, but with the barrier layers of paper between the Ni and SHS charge briquettes. It was shown that Ni melt in all three variants prevents the formation of the titanium silicon carbide MAX phase thus leading to its degradation. Ni introduction into the reaction mixture according to the first variant made it possible to obtain a homogeneous composite, which became almost non-porous with an increase in Ni concentration up to 50 %. When the Ni briquette was placed between two compacted briquettes of SHS charge, it was possible to melt a relatively small amount of Ni (23–29 % of the mass of synthesized composite samples), which was not enough to completely fill the porous layered skeletons of Ti₃SiC₂ . 20 % of Si added to the Ni briquette increased infiltration depth, lowered the degree of MAX phase degradation at the infiltration point, and formed a more homogeneous composite consisting of a porous skeleton of TiC, TiSi₂ and Ti₃SiC₂ phases partially filled with metallic nickel during Ni(Si) melt infiltration.

This mini review focuses on the analysis of the latest advances in the development of composite materials (CM) based on aluminum reinforced by micro and nanostructures. CM fabrication methods, different reinforcing additives (Al2O3, AlN, SiC, CuO, B4C, Li3N, C, BN) and their morphological types (nanotubes, nanoplates, micro and nanoparticles), and the structure and properties of CM are considered. The paper demonstrates the importance of theoretical modeling methods in studying the strength of interfaces in CM.

As a matter of discussion, the prospects for the development of high-temperature ceramic materials science are considered. The paper provides a rationale for developing hetero-modulus ceramic composites as a possibility to implement the unique physicochemical properties of refractory compounds (carbides, nitrides, borides, etc.) under the conditions of their application at high and ultra-high temperatures. The prospects of nanotechnology-based approach to the preparation of similar materials in engineering practice are shown.

The study covers the topography and structural phase state of VT1-0 and VT6 submicrocrystalline titanium alloy subsurface layers irradiated by high power pulsed carbon ion beams (ion energy is 250 keV, pulse duration is ~100 ns, pulse current density is 150–200 A/cm2; surface energy density of a single pulse is j ~ 3 J/cm2 when irradiating VT1-0 titanium alloy samples and j ~ 1 J/cm2 when processing VT6 titanium alloy samples; pulse number is 1, 5, 10, and 50). The surface of samples was subjected to preliminary mechanical grinding and polishing before irradiation. It was shown that surface defects are formed on the surface of the alloys after irradiation, namely craters of different shapes and geometries with a diameter from fractions of a micron to 80–100 μm. At the same time, the grain structure in the subsurface layer becomes more homogeneous in terms of grain size and equiaxial properties. The initial state of titanium alloys is characterized by a fairly homogeneous structure with an average grain size of ~0,31 μm for VT1-0 and ~0,9 μm for VT6. After one irradiation pulse, grain growth to 0,54 μm in the transverse direction is observed in the subsurface layer of the VT1-0 alloy (j ~ 3 J/cm2), while grain size decreases to ~ 0,54 μm in the VT6 alloy (j ~ 1 J/cm2). After 50 pulses, the average grain size in the subsurface layer reaches ~2,2 μm for the VT1-0 alloy and ~1,6 μm for VT6. It should be noted that a rather uniform structure with equiaxed grains is formed as early as after treating with 1 high power ion beam pulse.

The novel technology of multilayer coating deposition combining electric-spark alloying (ESA), pulsed arc evaporation (PAE), and magnetron sputtering (MS) in one vacuum process is presented. Layers can be deposited using a single electrode material at operating pressures from 0,1 Pa to atmospheric pressure. The lower ESA layer provides increased substrate toughness, perfect adhesion and a relatively high (up to 100 μm) coating thickness. The upper PAE or MS layer up to 10 μm in thickness provides high mechanical and tribological characteristics. The technology of double-layer PAE–ESA and MS–ESA coating deposition was tested on substrates made of structural and tool steels, titanium alloys using electrodes of cemented carbides (WC–Co, TiCNiAl) and carbon (low-porous graphite).

The paper describes the technology of producing a wear resistant silicon nitride coating on cemented carbide cutting tools and factors affecting its structure and thickness. A review of domestic and foreign authors’ works is given on the properties and applications of cemented carbides in cutting, drilling, die stamping tools, wear resistant materials, for chipless processing of wood, plastics. It is noted that one of the promising ways of cutting tool development is using indexable throwaway inserts (ITI) with wear resistant coatings. The choice of silicon nitride as a material for cemented carbide tool coating is justified. The data on silicon nitride deposition methods, investigation of cutting tool structures and properties are provided. Laboratory and factory tests of Si3N4-coated cemented carbide tools demonstrated coating applicability in improving the wear resistance and lifetime of cutting inserts.