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Surface-waterlogged soils drained by ceramic and plastic drainage are an analogue of large-area lysimetric installations, the drainage runoff in which is represented by gravitational waters similar to lysimetric waters. The drainage runoff module in spring and autumn and its dependence on the humidity of the year have been determined on test plots drained by plastic and ceramic drainage. It is shown that drainage transforms the stagnant-washing water regime into the washing type. The long-term and spatial dynamics of the removal of the clay fraction of soils and iron compounds has been studied. The leaching of chemical elements with drainage runoff and its effect on the intensity of lessivage in agro-gray drained soils have been revealed.

This article compares the microstructures of alloys formed upon the sintering of powdered mixtures of tungsten (PV2, average particle size 3.8–6.0 μm) and copper (PMS–11, particle-size fraction 45–60 μm) produced by various methods: the simple mixing of powdered metals, the mechanical activation (MA) of powdered metals, and the deposition of copper from a solution of its sulfate (Cu2SO4·5H2O) on powdered tungsten with simultaneous mechanical activation. The molar ratio in metals in mixtures is Cu/W = 1. The aqueous solution for copper deposition is comprised of diethylene glycol (up to 30%), glycerol (up to 8%), hydrofluoric acid (up to 0.1%), and the OP-10 wetting agent (up to 0.8%). Mechanical activation is carried out in an AGO-2 planetary mill with a drum load of 200 g of steel balls and a drum rotation speed of 2220 rpm for 5 min. Reduced copper in the solution and in air is rapidly oxidized to Cu2O; therefore, the composite powders were washed, dried, and stored in an argon environment. The samples pressed from the powders (tablets with a diameter of 3 mm, height of 1.5–2.0 mm, and density of 7.7–8.0 g/cm3) are sintered in argon at ambient pressure and in a temperature range from 1000 to 1500°C. During the sintering of Cu–W composite particles, it is possible to highlight several regions of the progress of the process. At temperatures below the melting point of copper, solid-phase sintering in the contact points of composite particles occurs. Upon heating from the melting points to 1200°C, the samples from the mixture of powdered metals are sintered according to the liquid-phase mechanism, forming a low porous cake. Sintering of composite powders produced by MA upon copper deposition and the MA of mixtures of powdered metals results in the segregation of samples with the formation of coarse pores extended perpendicularly to the axis of pressing and are partially filled with molten copper. Upon the heating of samples produced by the MA of powders above 1400°C, phase separation occurs and all copper is displaced from the sample to the surface.

CuCr composite particles have been obtained using copper deposition from the solution of its sulfate onto chromium powder particles with the simultaneous mechanical activation (MA) of the mixture in an AGO-2 planetary ball mill for 5 min. The CuSO4·5H2O concentration in the solution with complete copper reduction provides a molar ratio of Cu/Cr = 1. Since deposited fine crystalline copper is highly active and rapidly oxidizes to Cu2O oxide in air, the composite powders are washed, dried, and stored in an argon atmosphere. After drying, the mixture is subjected to additional MA for 5 min. During MA, composite particles with a laminate structure start forming in the solution. The powders are used to press tablets with a diameter of 3 mm, height of up to 1.5 mm, and density of 4.2–4.5 g/cm3. Samples are sintered in an argon atmosphere at 700–1400°С. To compare microstructures, we have also sintered samples from mixtures of Cr and Cu metal powders with a volume ratio of chromium to copper of 50 : 50, which were obtained by simple mixing in a porcelain mortar for 20 min and MA for 10 min. Three regions of the alloy structure formation can be distinguished depending on the heating temperature. When temperatures are heated below the eutectic melting point, composite particles are sintered at separate points. With heating temperatures above the liquidus temperature, the alloy melts with its phases separated; one part of the sample consists of copper enriched in chromium, and the other part consists of chromium enriched in copper. With intermediate heating temperatures, liquid phase sintering accompanied by phase separation is observed. Copper-enriched chromium particles become spherical and are located in a chromium-enriched copper matrix. A comparison of samples sintered under the same conditions from powder mixtures obtained by different methods showed that samples with deposited copper have a more uniform and fine-grained structure.

An intermetallic alloy based on the Heusler phase—Cu2TiAl—has been obtained by self-propagating high-temperature synthesis (SHS) in the Cu–Ti–Al system for the first time. The modes of frontal combustion of the green mixtures and the processes of phase formation during synthesis have been studied. The resulting products have been studied by X-ray analysis (including high-temperature diffractometry with step heating up to 900 K), scanning electron microscopy, and differential thermal analysis (DTA), and some physical properties have been studied. Electrophysical and magnetic measurements are also carried out for the alloy. The results of X-ray analysis and scanning electron microscopy using energy-dispersive analysis (EDA) have shown that the content of the Heusler phase in the synthesized product is at least 82%. The product also contains copper (CunineAl4) and titanium (Ti3Al2) aluminides. The temperature dependence of the electrical resistivity of the synthesized product is measured for a wide temperature range of 90–1000 K. The resistivity at T = 300 K is 0.3 μm Ωm. The metallic type of conductivity for obtained samples and the anomalous behavior of the temperature curve of electrical resistance in the region of 770–790 K are revealed. Thermal analysis is used to measure the melting point of the synthesized product and reveal additional heat effects at 788, 848, and 1248 K associated with possible phase transitions in the Cu2TiAl intermetallic compound. One possible mechanism of these phase transitions is considered in accordance with the phase diagram of the Cu–Ti–Al system. Magnetic measurement results show that intermetallic samples of the compound obtained by the SHS method exhibit weak ferromagnetic properties with residual magnetization of 0.069 A m2/kg.

To fabricate Cu–Ti composite particles, the method of copper deposition from its sulfate solution on titanium powder particles with the simultaneous mechanical activation (MA) of the mixture in an AGO‑2 planetary ball mill for 5 min is used. The CuSO4 ⋅ 5H2O concentration in solutions is 10 and 16%, which provides molar ratio Cu/Ti = 0.85 and 1.36, respectively, with the complete reduction of copper. The rapid reduction of copper in the form of highly dispersed partially amorphized powder occurs during MA, and composite particles with a thin laminate structure and high reaction ability are formed. Prepared composites are rinsed and stored in argon because reduced copper possesses high activity and rapidly oxidizes in air to oxide Cu2O. After drying, the additional MA of the mixture is performed for 5 min. Pellets 3 mm in diameter and up to 1.5 mm in height are compacted from prepared powders and heated in argon to 700–1200°C. An intense reaction with heat liberation (heat explosion) and the formation of TiCu, Ti2Cu3, and Ti2Cu intermetallic compounds starts upon sample heating. The critical inflammation temperature for composite powders formed by MA with simultaneous copper deposition from the solution is 480°C, which is 400°C below the inflammation temperature of the usual powder mixture of titanium and copper. The alloy has a dendritic structure at a heating temperature close to the melting point, while, if it is exceeded by more than 100°C, the phase distribution in the alloys becomes more uniform and their size decreases.

Composition/structure of products formed upon frontal combustion of Si powder in gaseous carbon dioxide at P(CO2) = 0.4–5.0 MPa were characterized by chemical analysis, XRD, and SEM/EDS. Combustion products were found to contain SiC, unreacted Si, and SiO2. Our results may turn interesting to those engaged in fabrication of heat-resistant Si–O–C ceramics.

Nanostructured mechanical composites of immiscible metals Cu, Cr, and 5–70 wt % W; nanostructured consolidated materials based on them; and Cu/Cu–Cr–W nanostructured gradient material with various W contents are fabricated in this work by combining short-term (up to 150 min) high-energy ball milling (HEBM) and spark plasma sintering (SPS). To fabricate Cu–Cr–W mechanical composites, HEBM of Cu + Cr + (5–70 wt %)W is performed using an Activator-2S planetary ball mill with a revolution rate of drums of 1388 rpm and a planetary disc of 694 rpm in argon for 150 min. The Cu–Cr–W mechanical composites are consolidated by SPS at temperatures of 800–1000°C and pressure of 50 MPa for 10 min. The nanostructured gradient sintered material based on Cu–Cr–W pseudoalloys is compacted layer-by-layer in the following sequence (from pure copper to pseudoalloy with an increase in the tungsten weight fraction): Cu/Cu–Cr–5% W/Cu–Cr–15% W/Cu–Cr–70% W and sintered at 800°C for 10 min. The crystal structure, microstructure, and properties of Cu–Cr–W mechanical composites and consolidated materials based on them are investigated depending on fabrication conditions. It is shown that the nanostructure formed in mechanical composites at the short-term HEBM stage (up to 150 min) is retained after SPS for all Cu–Cr–W (5–70 wt % W) compositions. The SEM and EDS data evidence that W (d ~ 20–100 nm) and Cr (d ~ 20–50 nm) refractory particles are homogeneously distributed in the material bulk (in a copper matrix). The hardness of consolidated Cu–Cr–W samples (15 wt %) formed from nanostructured powder mixtures (after 150-min HEBM) by SPS at t = 800°C exceeds the hardness of samples sintered from the mixture of initial components (without HEBM) by a factor of ~6. The hardness for the nanostructured Cu–Cr–70% W composition (tSPS = 1000°C) is higher by a factor of ~3 than for microcrystalline analogs. Samples Cu–Cr–15% W and Cu–Cr–70% W have the largest relative density up to 0.91. The resistivity of nanostructured Cu–Cr–W compositions exceeds this characteristic for microcrystalline samples approximately twofold. This can be caused by an increase in grain boundaries and the accumulation of various defects in the material at the HEBM stage. These results show the prospects of using the combination of short-term HEBM and subsequent SPS for the formation of consolidated nanocrystalline Cu–Cr–W composites and gradient materials based on them.

A cast material based on the Nb2AlC MAX phase is formed by SHS metallurgy. The synthesis is performed using the Nb2O5–Al–C mixture with the CaO2–Al high-energy additive. The results of thermodynamic calculations correlate with the experimental data. The substantial influence of the CaO2–Al additive on the thermodynamic parameters and phase composition of the product is established. It is shown that the synthesis using mentioned mixtures occurs in a stationary mode with the formation of a steady combustion wave. The combustion rate increases from 6 to 12 mm/s with an increase in the additive content, and the product yield into the ingot increases from 30 to 47% (up to 15 wt % additive) and then decreases. The variation in the composition of initial mixtures can substantially affect both the synthesis parameters and the phase composition of products. The optimal synthesis conditions of the materials that provide the maximal yield of the Nb2AlC MAX phase in the ingot composition are established. The determining factor that affects the Nb2AlC content in the product is the liquid-phase lifetime under the synthesis conditions. It is shown that the maximal amount (67 wt %) of the Nb2AlC phase is attained with the content of the high-energy additive in the initial charge of 15 wt %.

Shock-induced chemical transformations in Ti–B–Ni and Ti–C–Ni powder blends were explored by XRD and EDS methods (flyer velocities 1000 and 1500 m/s). The blends based on Ti–C showed lower sensitivity to shock compression compared to those based on Ti–B. Synthesized products comprised of TiC or TiB2 grains in a Ti–Ni binder. Preliminary mechanical alloying of reactive mixtures was found to elevate their sensitivity to shock compression. The obtained results may turn helpful in designing and optimizing the processes for fabrication of layered cermets.

Fine powders of pure Si2N2O were SHS-produced under pressure of nitrogen gas from mixtures doped with FeCl3 · 6H2O, and the influence of process conditions was explored by XRD and SEM/EDS. Pure 2D-nanopowders of Si2N2O were obtained in the presence of 15 × 10–3 M FeCl3 · 6H2O in green 3Si + SiO2 mixture at P(N2) = 5 MPa.

The results of studying the influence of mechanical alloying (MA) on the surface morphology, microstructure, and atomic–crystalline structure of particles of the Fe–Cr–Co–Ni–Mn multicomponent powder mixture are presented. The initial components are as follows: the R-10 radio-engineering carbonyl iron powder with average particle size d = 3.5 μm, the NPE-1 nickel powder with d = 150 μm, the PK-1u cobalt powder with d < 71 μm, the PKh-1M chromium powder with d < 125 μm, and the MR0 manganese powder with d < 400 μm. The MA of the prepared mixture was performed in an AGO-2 water-cooled mechanical activator using 9-mm steel balls with an acceleration of 90 g in air. The alloying time varies from 5 to 90 min. The ratio of the ball weight to the mixture weight is 20 : 1. X-ray diffraction patterns of the initial and alloyed mixtures, as well as of the sample formed by sintering, are recorded using a DRON 3M diffractometer in FeKα radiation at 2θ = 30–100°. The microstructure of the mixture particles and the compact sample metallographic specimen after sintering are investigated by scanning electron microscopy. It is established that the peaks of initial components are absent in the X-ray diffraction pattern after mechanical activation for 90 min, and peaks corresponding to the phase representing the γ-Fe-based solid solution having a face-centered crystal lattice are presented. Herewith, the fraction of the amorphous phase increases to 20%. A compact single-phase material is formed from the mixture prepared after 90-min alloying by spark plasma sintering at 800°C for 10 min. Its density is 7.49 kg/cm3, resistivity is 0.94–0.96 × 10–6 Ω m, and microhardness is 306–328 kg/mm2. The phase is uniformly distributed over the volume.

TiZrNiCuAl and TiNbNiCuAl alloys were prepared by thermal explosion and high-energy ball milling, characterized by SEM, XRD and tested for their thermal stability.

The effect of iron-containing catalysts–FeCl3 · 6H2O, Fe2(C2O4)3 · 5H2O, and Fe(NO3)3 · 9H2O–on phase composition, morphology, and particle size of products formed upon combustion of Si–C mixtures in nitrogen gas. Composition and granulometry of combustion products were found to depend on a type and amount of the above additives to green composition. The results may turn interesting for researchers active in the synthesis of refractory silicon compounds.

For W–Tf–Al mixtures, we investigated the behavior of burning velocity, gas evolution parameters, and composition of combustion products as a function of green composition and green density. Aluminum was used as a booster that increased the combustion temperature and decreased the ignition temperature. With increasing green density, the burning velocity and gas evolution rate were found to decrease.

The results of the investigation into the formation of amorphous structures in the Cu–Ti system and their subsequent crystallization under the effect of high-energy ball milling (HEBM) are presented. To form amorphous Cu–Ti powders, powders of copper (MPS-V grade with average particle size d = 45–100 μm, GOST (State Standard) 4960–75) and titanium (PM99.95, d = 2.0–4.5 μm, TU (Technical Specifications) 48-19-316–80) are selected as the initial components. The HEBM of Cu + Ti powder mixtures is performed using an Aktivator-2S laboratory planetary ball mill (at revolution rates of discs of 694 rpm and drums of 1388 rpm) for 1–30 min. The investigations into the surface morphology and micro-, nano-, and atomic crystalline structure of activated Cu + Ti powder mixtures are fulfilled by X-ray structural analysis (XSA) using a DRON-3M diffractometer, scanning electron microscopy using a Zeiss Ultra+ microscope (Germany) with the application of energy dispersive analysis, and high-resolution transmission electron microscopy (TEM) using a Titan microscope (United States). The determination of thermal characteristics of phase transformations (temperature, heat of reaction, and amorphous-to-crystalline transition) are performed by differential scanning calorimetry using a DSC 204 F1 device in the mode of linear heating to 450°C at a rate of 20 K/min. The Cu–Ti amorphous powders were fabricated using HEBM for 20 min. The XSA data evidence that the fraction of the amorphous phase in the material was 93%. The TEM investigations showed that the material preferentially consists of the amorphous phase with an insignificant content of nanocrystalline regions 2–8 nm in size. It is found that the Cu–Ti amorphous phase crystallizes in a temperature range of 336–369°C, and the heat of reaction is 79.78 J/g.

Impact of ammonium acetate and ferric chloride additives on the SHS of polycrystalline silicon nitride fibers in nitrogen gas was investigated by XRD, SEM, and EDS. Our results suggest that the metallic drops formed in reactions of gaseous СО, SiО, and Si with Fe on the surface of the Fe–Si–С globules are capable of initiating the growth of 1D nanocrystals by the VLS–root mechanism.

Explored was the influence of compacting pressure (P) and green density (ρ) on the properties of Zr-doped mineral-like pyrochlore ceramics Y2(Ti1 – x Zr x )2O7 (x ≤ 0.3) prepared by SHS method. The optimal ρ values that provide minimal porosity and maximal mechanical strength of synthesized ceramics were found. An increase in ρ was found to decrease combustion temperature and increase pyrochlore lattice parameter a. Green density was also found to affect phase composition of the SHS-produced ceramics under study.

Mineral-like Y2(Ti1–x Zr x )2O7 ceramic matrices for immobilization of actinide–Zr–RE-containing high-level nuclear wastes (HLW) were prepared by SHS method. In experiments, HLW were modeled by a mixture of CeO2, La2O3, ZrO2, MnO2, and Fe2O3 powders. An increase in the HLW content of green mixture decreased the amount of Y2(Ti1–x Zr x )2O7 in combustion product and increased that of ZrO2, LaTiO3, and CaTiO3; decreased the fractional substitutionality of Zr for Ti; and increased the product porosity. An increase in combustion temperature and suppression of heat sink during SHS reaction did not diminish markedly the porosity of synthesized ceramics.

Thermal explosion in (Ni + Al)/Nb/(Ni + Al + Nb) sandwiches was found to results in formation of (a) NiAlNb composite containing NiAl, NiAlNb, and trace amounts of Nb5Ni and (b) good joining with a transition zone.

Cast ceramic composites were prepared by metallothermic SHS under elevated Ar pressure (5 MPa). Variation in green composition was used to affect the phase composition of combustion products. Under some optimized conditions, resultant ceramics can be obtained in the form of Al2O3–Cr2O3 solid solutions, Al2O3–Cr2O3 ∙ хZrO2 composites or single-phase Al2MgO4. Such materials seem promising for use in jewelry, process engineering (casting molds, cutting tools), and aerospace industry.

Explored was the deposition of multilayer TiCx–TixSiy-based coatings onto Ti substrate by SHS method. Sandwich-type green multilayer structures were assembled from Ti foils and Ti + 0.5C, Ti + Si, 5Ti + 3Si, and Ti + 0.65C pellets and ignited under 1 atm of Ar and a load (400 g). Burned sandwiches were characterized by SEM, EDS, and XRD. In all cases, we observed good metal–ceramic joining. Prerequisites for such a joining are (i) the presence of the liquid phase in combustion products, (ii) good metal–ceramic wettability, and (iii) closeness of reaction temperature to the melting point of substrate.

Boron carbide is prepared by self-propagating high-temperature synthesis (SHS) in a composition range from 5 to 30 at % carbon. The introduction of an inert (MgO) and active (Mg(ClO4)2) additives into the reaction mixture leads to a variation in process parameters such as the temperature and combustion rate. It is established that the unit cell metrics of boron carbide substantially vary depending on the synthesis conditions. The degree of the effect of the SHS mode on the crystal structure rises with an increase in the carbon fraction in the boron carbide structure. This regularity is associated with the ordering diversity of carbon atoms in nonstoichiometric boron carbide. No influence of the synthesis conditions on the unit cell parameters is observed for stoichiometric boron carbide, which is associated with the structure saturation with carbon. It is shown that the variation in the combustion temperature during SHS of boron carbide of the same composition leads to the variability of the structural parameters, thus reflecting the influence of the synthesis conditions on the material crystal structure.

For products of thermal explosion in Ti–Nb–2Al, Ti–Nb–2.5Al, and Ti–Nb–3Al compacts, investigated were their morphology, phase composition, microstructure, and some physical parameters. Best homogeneity and lowest porosity were shown by the products derived from Ti–Nb–3Al compacts. The main product of thermal explosion was tetragonal γ-TiAl with a distorted lattice, tentatively a solid solution of Nb in TiAl.

Dispersion-strengthened TiAl3-based material with uniform structure and high compression strength (σc ≈ 850 MPa) was SHS-produced from Ti–Al–B4C blends in a mode of thermal explosion by using the B4C particles coated with a TiB2/TiC layer as a strengthening agent and preliminary mechanical activation of Ti–Al powder mixtures. The Ti + 3Al mixtures were mechanically activated in a planetary mill for 3 or 6 min and then 10 or 20 wt % of coated B4C particles were added. Pelleted samples were placed into a reaction chamber and heated in an electric furnace under Ar to a self-ignition temperature. The process was optimized and recommended for practical implementation.

Magnesiothermic SHS from reactive mixtures containing energy-producing additive, Mg(ClO4)2, in green mixtures was used to explore crystallization of boron carbide and its derivatives in a large SHS reactor in conditions of strong temperature gradients within the sample bulk. The addition of Mg(ClO4)2 increased a maximum combustion temperature (Tc) up to 2500°C (instead of 2000°C without the additive). The presence of gasifying agent resulted in a non-uniform distribution of combustion products. Except for the central sample area with a maximum value of Tc, the product exhibited the cell parameters corresponding to stoichiometric B4C. A two-phase material formed in the central zone was found to contain B13C2 and B25C4Mg1.42. This was explained by different temperature conditions in different areas of the sample bulk.

Boron carbides of varied composition were synthesized through magnesiothermic SHS reaction at temperatures between 1500 and 2500°C and characterized by XRD. Variation in synthesis temperature was found to change the lattice parameters of boron carbide, which was associated with the disordering of the crystal structure.

Reactions of SHS hydrogenation in Me-H systems (Me = Ti, Zr, Hf) were explored by time-resolved XRD. The SHS reaction yielding TiH2 was found to proceed in the following stages: α-Ti → α-Ti[H] → β-Ti[H] → δ-TiH2 (here β-Ti[H] stands for solid solution of hydrogen in β-Ti). SHS hydrogenation of Zr took place by the following scheme: α-Zr → β-Zr[H] → δ-ZrH1.5 → ɛ-ZrH2. The α-Hf → δ-HfHx transformation happened in one stage, without formation of intermediate β-Hf[H]. Our results shed new light on the kinetics and mechanism of SHS hydrogenation of metals.

Ferrites NiMn x Fe2 − x O4 (x = 0.0, 0.2, 0.4, and 0.6) were synthesized by SHS and hot sintering and comparatively characterized by ESM, EDS, and XRD; and a tentative mechanism of SHS reaction was suggested.

Ni-Al intermetallics dispersion-strengthened with silica, alumina, and mullite were prepared by SHS under load and characterized by XRD and SEM/EDS. The observed formation of a transition zone between the embedded mullite particles and NiAl matrix in combustion-synthesized NiAl-mullite composites can be expected to improve the service parameters of thus synthesized material.

Combustion of Ni-Al mixtures was explored by time-resolved XRD within the homogeneity range for NiAl. Unconventional behavior of the strongest (110) NiAl peak was observed: with decreasing temperature, the initially narrow peak became broadened and then split into several components that merged during subsequent cooling down. This observation is thought to reflex the complicated kinetics of the phase transformation from the high-temperature (around 1600°C) disordered [Ni,Al] solid solution (space group Im3m) to the low-temperature fully ordered NiAl phase (space group Pm3m).

(Mo,W)Si2, (Mo,Nb)Si2, and (Mo, Ti)Si2 silicides and their solid solutions were prepared by the technique of SHS casting under 5 MPa of Ar pressure from thermit-like green mixtures containing the oxides of Mo, Nb, and Ti as well as activating 3CaO2 + 2Al additives. The synthesized composites were characterized by XRD and EDS.

Boron carbides with carbon contents (σ) of 7–24 at. % were prepared by SHS method and their lattice parameters were determined by high-precision XRD analysis. An unusually wide spread in the literature data on lattice parameters of boron carbide as a function of σ was associated with the process of crystal ordering caused by gradual replacement of boron by carbon atoms. For SHS-produced boron carbide, the above spread turned out minimal. Lattice parameter c was found to attain the unusually high values of 12.20–12.31 s was observed at σ = 13.2%. The widths of diffraction lines from boron carbide were found to depend on σ and attain their maximum values at σ = 13.2% when the lattice is most disordered. Our results can make a basis for elaborating the means for regulating the structure/properties of boron carbide.

Ultrafine MoSi2 powders were prepared by SHS reaction from the elements (under an Ar pressure of 5 atm) followed by optimized diminution process and chemical dispersion (hot alkali etching). Raw SHS products (cakes) were found to contain tetragonal MoSi2 and an admixture of Mo4.8Si3C0.6. Chemical dispersion of ground product yielded MoSi2 powders in the form of porous agglomerates. The precipitates containing 50% MoSi2 and 50% K2MoO4 were separated from etching solutions. The size of MoSi2 particles was below 100 nm.