The process of mechanochemical synthesis of titanium carbide in the ternary system Ti-C-50 wt.% Cu at a stoichiometric Ti:C ratio was studied using X-ray phase and Xray structural analysis. It is shown that the mechanochemical synthesis proceeds in a mode of mechanically stimulated reaction involving the liquid phases of copper and titanium, as the calculated adiabatic temperature in the ternary system Ti-C-50 wt. % Cu is significantly higher than the melting points of copper and titanium. The induction period of the mechanically stimulated reaction lasts 110 s, followed by a sharp jump in the reaction rate of titanium carbide formation, and within the next 10 s, 85 wt. % TiC with an ordered structure and a composition close to stoichiometric is formed, with crystallite sizes of ~ 47 nm and a low level of microdeformations of ~ 0.24 %. Within the same time frame (120 s), a solid solution of Cu(~ 2 % Ti) with a microdeformation level of ~1 % is formed. Activation for 2–4 min results in the carbon content in titanium carbide and increases the titanium saturation of the solid solution based on copper. An increase in activation time to 16 min leads to the disordering of the titanium carbide structure and carbon depletion, the Cu(Ti) solid solution decomposes, and secondary titanium carbide is formed.

In this study, TiC-Ni composites were fabricated in situ by high-energy ball milling of Ti-C-Ni powder mixtures followed by spark plasma sintering (SPS) at 1000 and 1100 degrees C. Three compositions were chosen: 30 wt%(Ti-C)- Ni, 40 wt%(Ti-C)-Ni, and 50 wt%(Ti-C)-Ni. During milling, the TiC phase was synthesized and dense nano- structured powder agglomerates of TiC-Ni were formed. The compaction of the products of milling via SPS was accompanied by local melting of the material at the inter-particle contacts caused by high electric current densities. The TiC-Ni composites fabricated by SPS at a temperature of 1100 degrees C showed relative densities of 98-99 %. Partial melting helps reduce the porosity as pores are filled with the melt. When this melt re-solidifies, nickel-rich regions form in the structure. The phase composition of the materials subjected to SPS is represented by a nickel-based solid solution and non-stoichiometric titanium carbide TiC 0.65-0.8 . The size of TiC reinforcing particles in the sintered composites is less than 1 mu m. The Vickers hardness of the composites obtained by SPS at a temperature of 1100 degrees C from mixtures 30 wt%(Ti-C)-Ni, 40 wt%(Ti-C)-Ni and 50 wt%(Ti-C)-Ni was 740 f 10 HV1, 910 f 20 HV1 and 980 f 30 HV1, respectively.

The article considers the mechanochemical preparation of TiC-Ni composites in reaction mixtures of Ti-C-Ni powders and the formation of the structure of materials during their sintering under pressure. The synthesis was carried out in an AGO-2 planetary ball mill with a mixture processing time of 12 and 20 min; their subsequent sintering was performed at a temperature of 950 °C and a pressure of 130 MPa. The results of diffraction studies are presented for structural-phase transformations in mixtures of equimolar composition of titanium and carbon depending on the nickel content in the range of 50–70 wt.%. It is established that an increase in the Ni concentration leads to a decrease in the size of the formed TiCx crystallites from 29 ± 1 to 16 ± 1 nm. A high carbon content TiC0.88–0.98 carbide is formed in Ti-C-(50 and 60 %)Ni compositions and non-stoichiometric TiC0.62–0.78 at 70 % Ni. The microstructure of dispersion-strengthened grains of the nickel solid solution is formed during sintering of TiC/(50–60 %)Ni mechanocomposites. Titanium carbide inclusions have a spherical shape and a diameter of 60–100 nm. When sintering TiC/70%Ni, depleted titanium carbide has a grain boundary distribution with the formation of large (~400 nm) agglomerates. The microhardness of sintered materials is in the range of 850–900 HV.

The structural and phase evolution of powders in a Ni–Ti–C ternary system with 50 wt

Using methods of X-ray structural analysis, scanning electron microscopy, and Mössbauer spectroscopy, the features of the structure formation in powder systems Fe–Ti, Fe/Ti–diamond and Fe–Ti–C during mechanical alloying under the conditions of the planetary ball mill AGO-2 (energy intensity 7 W/g) were studied. It is shown that titanium and iron with limited mutual solubility under high-energy mechanical impact with a duration of 20 min interact to form an alloy of nanostructured iron and grain boundary phases of the type solid solutions Fe(Ti), Ti(Fe), and FeTi with a total 22–24 % content. In the composition of Fe-20 % Ti, titanium reaches an X-ray amorphous state, and at a titanium content above 20 wt % , the crystalline phase α -Ti is preserved in the amount of 5–10 wt % . During mechanical activation of the Fe/Ti–diamond mixture, composite particles are formed with a size in the range of 2–12 μ m, with a metal matrix structure with a diamond particle size of 0.3–1.5 μ m. It has been established that titanium accelerates the process of grain boundary and bulk interaction of iron with diamond and titanium carbide. In the studied powder compositions, a solid solution based on iron and TiC, Fe _3 C compounds is formed with their total content: Fe/40 % , Ti–diamond up to 62 % ; Fe/TiC up to 34 % . Under similar conditions in the diamond–iron mixture, grain boundary phases of the solid solution do not exceed 26 % . The formation of graphite has not been detected by X-ray diffraction.

The products of mechanically stimulated interaction of NiO with Al were studied by X-ray diffraction and IR spectroscopy. Composites Ni/α-Al2O3, NiAl/α-Al2O3, Ni2Al3/α-Al2O3 can be fabricated by varying the ratio of initial components under the selected conditions of mechanical activation. The approach under consideration, based on a mechanically stimulated reaction, makes it possible to significantly simplify the previously proposed method of mechanically activated self-propagating high-temperature synthesis and produce nanostructured composites.

The influence of the conditions of mechanical activation of a mixture of Cu–12 wt. % Sn with different content of the modifier Cu9 Al4 on the structural-phase composition and morphology of the formed composites was studied by the methods of X-ray diffraction analysis, optical and electron microscopy. With the mechanochemical introduction of 10 wt. % of the modifying additive into the matrix of mechanosynthesized tin bronze, the product mainly forms a ternary solid solution of aluminum and tin in copper, Al0.05Cu0.9Sn0.05. In the case of 20 wt. % of the modifying additive, the product contains a solid solution of tin in copper Cu0.9Sn0.1 and an intermetallic compound Cu9 Al4. Studies of the mechanical and tribotechnical characteristics of the material obtained by sintering under pressure showed that the intensity of wear of bronze of the mechanochemically synthesized powder Cu–12 wt. % Sn is slightly less than that of industrial bronze BrTPh10-1, the friction coefficient f decreases by a factor of 1.4, and the range of its values is quite wide f = 0.7–0.9. Modification of mechanically synthesized Cu–12 wt. % Sn bronze with the Cu9 Al4 intermetallic compound makes it possible to reduce wear by a factor of 1.4–1.8 and significantly reduces the friction coefficient (by a factor of 2). A stable value of f = 0.5 is achieved for the MA composition Cu–12 wt. % Sn + 20 wt. % Cu9 Al4. The introduction of an intermetallic compound increases the microhardness of the alloys by a factor of 1.6–2.0 (up to Hμ = 2730 MPa) relative to the bronze alloy BrTPh10-1and mechanically synthesized bronze.

The structural-phase state of a powder mixture of copper and tin (X = 12–20 wt

X-ray diffraction analysis and optical and electron microscopy have been used to study the effect of mechanical activation conditions of the Cu–12% Sn mixture with different Cu 9 Al 4 modifier contents on the structure and phase composition and morphology of formed composites. The mechanochemical introduction of 10 wt % of the modifying additive into the matrix of mechanically synthesized tin bronze mainly results in the formation of a ternary Al 0.05 Cu 0.9 Sn 0.05 solid solution of aluminum and tin in copper. In the case of the 20 wt % modifying additive, the final product contains a Cu 0.9 Sn 0.1 tin solid solution in copper and Cu 9 Al 4 intermetallics. Studies of the mechanical and tribological characteristics of the material prepared by sintering under a pressure showed that the intensity of wear of the material based on the Cu–12 wt % Sn mechanochemically synthesized bronze is insignificant lower than that of commercial bronze alloy CuSn10P; the coefficient of friction ( f ) decreases by ~1.3 times and the range of its values is sufficiently wide, f = 0.7–0.9. The modification of the Cu–12 wt % Sn mechanically synthesized bronze with the Cu 9 Al 4 intermetallics allowed us to decrease the intensity of wear by 1.3 to 1.6 times and to substantially decrease the coefficient of friction (by 1.2 to 1.6 times). The stable value f = 0.5 is reached for the mechanically activated Cu‒12 wt % Sn + 20 wt % Cu 9 Al 4 composition. The introduction of the intermetallics results in the increase in the microhardness of the alloys by 1.6 to 2 times (to H μ = 2730 MPa) compared to those of CuSn10P and mechanically synthesized bronzes.

The results of studies of the structural-phase state of copper and tin mixture powders (12-20 wt.% Sn), formed during high-energy mechanical processing in a planetary ball mill, are presented. The effects of mechanochemical synthesis of composites during sintering and formation of the structure of sintered bronzes are considered. The relationship between the tin content and the formation of grain-boundary segregations and their influence on the properties of materials is shown. Thus, an increase in the concentration of tin contributes to the acceleration of grain-boundary interactions, a decrease in the rate of bulk diffusion, followed by the formation of supersaturated bulk and grain-boundary solid solutions. For the composition of the mixture with a tin content of 18-20 wt.% during mechanochemical synthesis, grain-boundary supersaturation with tin is achieved by more than 2 times, which contributes to dispersion strengthening of sintered materials based on them and provides microhardness within 2.1-3.0 GPa in a temperature range of 20-800 °С.

IR spectroscopy, electron microscopy, and X-ray diffraction analysis, including the application of synchrotron radiation, have been used to study the mechanochemical reduction of copper oxide with aluminum at the stoichiometric ratio of the components and in the presence of an excess of oxide-forming metal and aluminum solid solution in copper as well. The possibility is shown of the mechanochemical reduction of copper oxide with aluminum and aluminum solid solution in copper, which is accompanied by the formation of the Сu/Al 2 O 3 composite structure. To modify copper with alumina, using an aluminum solid solution in copper is preferable.

Cu–Al bronzes are interesting metallic materials, demonstrating higher hardness, higher wear resistance, higher corrosion resistance and a lower friction coefficient as compared with unalloyed copper. The powder metallurgy approach to the fabrication of these alloys presents opportunities to tailor their phase composition and grain size. In the present work, the structural characteristics, phase composition and properties of Cu-10 wt.% Al alloys obtained by spark plasma sintering (SPS) of powder blends and a powder obtained by mechanical alloying (based on Cu(Al) solid solution) are reported. Alloys with different interaction degrees between the metals were obtained by SPS. The blends demonstrated better sinterability than the mechanically alloyed powder: a nearly fully dense alloy was obtained by SPS of the blend at 480 °C, whereas a temperature of 800 °C was necessary to consolidate the mechanically alloyed powder. The hardness and electrical conductivity of the sintered alloys were comparatively analyzed. It was shown that the Cu-10 wt.% Al alloys obtained without the mechanical alloying stage possess hardness and electrical conductivity comparable to those of the alloys obtained from the mechanically milled powder.

Mechanochemically synthesized particles of two types of magnesium ferrites, one of which with structural distortions and an average size of 170 nm, and another that is highly crystalline with an average size of 900 nm, were introduced into a matrix of ultra-high-molecular-weight polyethylene via the milling processing. The final material has been formed by hot pressing mechanocomposites based on ultra-high-molecular-weight polyethylene and magnesium ferrite particles of various fineness and concentration. Structural characteristics were studied using scanning electron microscopy, differential scanning calorimetry and X-ray diffraction analysis. The dielectric properties of the obtained composites were analyzed by testing the frequency dependence of the permeability, dielectric losses, and conductivity. The effect of filler concentration and particle size, as well as the crystallinity of the polymer, on the dielectric properties of the composite material were studied.

The influence of the conditions of mechanical activation of a mixture of Cu-12 wt. % Sn with different content of the modifier Cu9Al4 on the structural-phase composition and morphology of the formed composites was studied by the methods of X-ray diffraction analysis, optical and electron microscopy. With the mechanochemical introduction of 10 wt. %of the modifying additive into the matrix of mechanosynthesized tin bronze, the product mainly forms a ternary solid solution of aluminum and tin in copper, Al0.05Cu0.9Sn0.05. In the case of 20 wt. % of the modifying additive, the product contains a solid solution of tin in copper Cu0.9Sn0.1 and an intermetallic compound Cu9Al4. Studies of the mechanical and tribotechnical characteristics of the material obtained by sintering under pressure showed that the intensity of wear of bronze of the mechanochemically synthesized powder Cu-12 wt. % Sn is slightly less than that of industrial bronze BrTPh10-1, the friction coefficientf decreases by a factor of 1.4, and the range of its values is quite wide f = 0.7-0.9. Modification of mechanically synthesized Cu-12 wt. % Sn bronze with the Cu9Al4 intermetallic compound makes it possible to reduce wear by a factor of 1.4-1.8 and significantly reduces the friction coefficient (by a factor of 2). A stable value off = 0.5 is achieved for the MA composition Cu-12 wt. % Sn + 20 wt. % Cu9Al4. The introduction of an intermetallic compound increases the microhardness of the alloys by a factor of 1.6-2.0 (up to H mu= 2730 MPa) relative to the bronze alloy BrTPh10-1and mechanically synthesized bronze.

The processes of mechanochemical reduction of oxides of iron, nickel, and copper with aluminum with a stoichio metric ratio of components and in mixtures with a two-, three-, and four-fold excess of the aluminum content over the stoichiometric, as well as in the presence of an excess of oxide-forming metal and solid solutions of aluminum in iron and copper, were studied by the Mössbauer and IR spectroscopy, X-ray diffraction analysis, including the use of synchrotron radiation, and electron microscopy. The conditions for formation of metals modified with aluminum oxide (iron, nickel, copper) and their monoaluminides are determined. High aluminum content aluminides are formed at a three-fold excess of aluminum, and at a four-fold excess, a mechanochemical reduction of oxides does not occur. The preferred method for modifying metals with alumina is the mechanochemical reduction of oxides with a solid solution of aluminum in the oxideforming metal. Mechanochemical interaction in the high-energy Hf–C system in the presence of 20, 30, and 50 wt. % copper leads to the formation of hafnium carbide; and with an increase in the copper content, the crystallite size decreases.

Scanning electron microscopy, X-ray diffraction, Raman and Mössbauer spectroscopies, field and temperature dependences of magnetic saturation and magnetocaloric effect in alternating magnetic fields are used to study submicron yttrium ferrite particles prepared by reverse coprecipitation from nitrate solutions at various pH values and subsequent heat treatment. The size, phase purity, and structural state of prepared particles determine the magnitude of the magnetocaloric effect exhibited by the particles in the external alternating magnetic field (370 kHz, 1.77 kA/m).

A fabrication route of Cu-10 wt% Al bronze via high-energy mechanical milling and spark plasma sintering (SPS) is proposed. SPS of the ball-milled powder at 700-800 degrees C allows obtaining single-phase Cu(Al) solid solution. Vickers hardness measurements and mechanical tests in compression were conducted on the sintered alloys. The electrical conductivity of the alloys was measured by the eddy current method. The alloy sintered at 800 degrees C shows an attractive set of properties: a hardness of 280 HV1, a proof stress of 760 MPa, a compressive strength of 960 MPa, a deformation at fracture of 5%, and an electrical conductivity of 15% of the International Annealed Copper Standard.

Introduction: The active biological substances used in medicinal and cosmetic applications, are mainly organic acids. The local contact effect of the protons located on the surface of their crystallites can irritate the mucous membranes of the stomach and esophagus (medicines), or skin of the face (cosmetics). The irritating effect of protons can be weakened either by grinding crystalline acid powders to nanoscale sizes, or by neutralizing them. Organic acids are polymerized due to hydrogen bonds, which does not allow them to be dispersed to nanometric sizes by traditional methods. It was previously shown that during the mechanical activation of silicates, short-lived hydroxyl groups become available. Objective: The purpose of this work is to study the possibility of neutralization of protons of organic acids during their mechanochemical interaction with silicates. Methods: The IR spectroscopy, X-ray analysis and electron microscopy methods were used for research. Results: It was shown by that organic acid is "grafted" to the silicate surface due to neutralization of organic acid protons by hydroxyl groups of layered silicates, opened during mechanical activation. This makes it possible to form highly dispersed composite structures "organic acid/layered silicate" in dicarboxylic (carboxylic, aromatic, amino) acids - talc (pyrophyllite, kaolinite) systems. Conclusions: Such mechanochemically synthesized composites, in which acid is grafted to an inert carrier, in addition to high dispersion, provide a decrease in the acidity of the resulting product. In the case of mechanochemical interaction of SiO2 with organic acids, the basic centers mainly work on the surface of SiO2 , which is opened during mechanical activation. Organic acids (hydroxo acids, dicarboxylic, carboxylic, aromatic) are distributed in an extremely thin layer on the surface of silicon oxide due to the "SiO2 — adsorption water — acid" bond. This allows to change the pharmacokinetics and avoid ulcerogenic action and reduce the irritating effect of organic acids on the skin.

Nearly fully dense metal-ceramic composites were synthesized by high-energy ball milling of (2Ta-C)+Cu powder mixtures followed by liquid phase-assisted spark plasma sintering (SPS). The concentration of copper in the starting mixtures was 30 wt% and 50 wt%, while the molar ratio of Ta/C was 2/1. The products of milling consisted of dense composite agglomerates. The agglomerates formed from (2Ta-C)+30 wt% Cu contained similar to 10 wt% of iron introduced as contamination during milling. In the sintered composite obtained from (2Ta-C)+30 wt % Cu, Fe5Ta3 was present along with TaC and Ta2C. The reinforcing phase in the composite obtained from (2Ta-C)+50 wt% Cu was Ta2C. During SPS, the formation of melt locally at the inter-particle contacts enabled consolidation of the agglomerates into compacts with a low residual porosity (2-5%). Composites obtained in this work possessed interesting structural features: a Cu-rich network penetrated the structure such that each composite particle was surrounded by a Cu-rich layer. The Vickers hardness of the sintered composites obtained from mixtures containing 50 wt% Cu and 30 wt% Cu was 490 +/- 50 HV1 and 715 +/- 55 HV1, respectively.