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The surface tension and density of Fe–C-containing melts with SiC and TiC0.8N0.16O0.04 nanosized phases have been investigated and show that the presence of SiC leads to a slight increase in the surface tension and the introduction of TiC0.8N0.16O0.04 leads to its decrease. It is shown that coefficients ∂σ/∂Τ of these melts without and with nanophases are positive. It is found that, with the introduction of nanophases into the metal, the density of the melts decreases and loosening increases. The composition of heterogeneous nonmetallic inclusions depends on nanophases: the introduction of SiC reduces the oxygen content in them, TiC0.8N0.16 O0.04 increases it, and the composition of homogeneous inclusions depends on the interaction of nanophases with sulfur and leads to a decrease in the element in them.

Per the literature, the thermodynamic stability criterion of the dispersed system of nanosized phases in metal melts is reproduced, with the latter considered the specific change in free energy (referred to the unit of change in the contact surface of the phases) of the disperse system aggregation. For iron–carbon melts with [C] > 2 wt %, according to the published scientific results, the selection of two refractory phases SiC and TiC0.8N0.16O0.04 for introduction into the Fe–C–Si–Mn–P–S–O melt is justified. The preparation of nanophases, the preparation of briquettes of a composite material, and the method used to study the interfacial interaction of nanophases with sulfur and oxygen of the melt is described. It is shown that a decrease in the surfactant content of the nanophase content upon 5–10 min of exposure indicates the interaction of the surfactant with nanoparticles, and the concentration dependences are characterized by extreme minimum values.

Advances in nanotechnology have made it possible to use nanosized particles for the modification of metals and alloys both in metallurgy and in welding. This article discusses the thermodynamic stability of titanium nitride nanosized particles in a molten pool on the basis of theoretical analysis and experiments. It is demonstrated that, upon the addition of titanium nitride to a molten pool, its dissociation should be expected in the overall temperature range; this has been confirmed experimentally.

This article discusses the possibility of introducing nanosized particles into a molten pool using a flux-cored wire. A flux-cored wire has been proposed with added composite granules obtained upon the combined treatment of nickel powder and nanosized particles. In order to avoid the overheating of particles, it has been proposed to add a flux-cored wire to a molten-pool tail using preheating. The following hardmelting particles have been tested: tungsten carbide (WC), titanium nitride (TiN), and aluminum oxide (Al2O3). It has been demonstrated that the addition of tungsten carbide to a molten pool improves the stability of weld-metal (WM) impact toughness while retaining its average value and the addition of aluminum oxide to a molten pool leads to increased average values of WM impact toughness while retaining its stability. Meanwhile, nanosized particles of titanium nitride in a molten pool are prone to dissociation, which leads to the formation of porosity, thus limiting the field of application of this modifier.

With the help of a complex of methods of disperse-structure analysis of nanopowders of plasmachemical synthesis, the function of particle-size distribution and its main characteristics—the average size and dispersion—are studied. A generalization of results of disperse characteristics for nanoparticles formed with the participation of various mechanisms—“vapor–solid” and “vapor–liquid–solid”—is carried out. It is shown that the formation of titanium nitride and carbonitride nanoparticles proceed on the vapor–solid mechanism without the participation of coagulative-particle growth. For the nanopowders under study, it is established that the variation range of standard deviation for the distribution function is in the interval of 30–60% of the average diameter; the index of aggregation is defined in the range of 1.5–3.0. It is revealed that the logarithmically normal function of particle-size distribution most authentically (with a correlation coefficient of more than 0.95) describes all studied objects for all mechanisms of particle formation in a wide range of dispersion of the received nanopowders independently of process parameters and organization of gas-disperse stream in the plasma reactor. Hypothetically, the established lognormal particle-size distribution is determined by the lognormal distribution of nanoparticles by residence time in the growth zone.

The characteristics of heat and mass transfer to the wall of a confined-jet plasma flow reactor on the basis of an electric arc plasmatron in the processes of nanopowder preparation from metals and their compounds are studied experimentally. Nanopowders are prepared from copper, tungsten, aluminum oxide, and a composition based on tungsten carbides. The heat flow distribution and the distribution of the mass flow of nanoparticles to the reactor surface at different parameters of the nanopowder preparation processes are studied.

This work presents the results of investigations into the interaction between nanoparticles of heatresistant phases (for the case of Al2O3 and TiN) with particle sizes of 30–100 nm and surfactants in a Ni-S melt accompanied by the subsequent removal of assemblies of nanoparticles of heat-resistant phases (NPHPs) + S to the interfaces Me-ceramics or Me-gas. A procedure for selecting nanoparticles for a specified metal and surfactant and a technique of adding nanoparticles into a melt in the form of composite material nanoparticles/(matrix metal) have been developed and substantiated. The sulfur removal rate upon heterophase interaction has been analyzed as a function of dimensional factors: the exposure time of nanoparticles in liquid metal, nanoparticle sizes, and the sulfur concentration in simulated melt. A variation in the surface tension and melt density has been studied upon the addition of nanoparticles; the influence of the essence and size of heat-resistant nanoparticles on these properties upon temperature variation has been demonstrated.

The results of an investigation into the microstructure of composite materials based on an aluminum matrix reinforced by intermetallic phases, which are formed by in situ reactions in the presence of nanosize ceramic particles, are presented. The possibility of modifying and stabilizing the structure of such composite materials with nanopoweder additives is determined.