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The influence of the environment and bacterial cultures on the degree of gold leaching from Au-containing raw materials of different compositions, origins, and with different contents of gold, selected in the Ural Federal District (Russia), was determined. The leaching degree was determined according to the change of the gold concentration in the ore by means of mass-spectrometry with inductively-coupled plasma. It was demonstrated that the degree of Au bioleaching from carbonaceous-argillaceous slates, containing 2.17 g/t of gold, and from pyritic technogenic raw materials, containing 1.15 g/t, when holding them in peptone water and Leten medium reached 92.17% and 87.83%, respectively.

The structural state and the quantitative phase analysis of the TiAl system, alloyed with rare-earth metals synthesized using hydride technology, were studied in this work. Using the Rietveld method, the content of the major phases in the initial system Ti(50 at.%)–Al(50 at.%), as well as Ti(49 at.%)–Al(49 at.%), with alloying additions Ta, Y and Dy having a high accuracy was determined. The methods of scanning electron microscopy, transmission electron microscope and X-ray spectral microanalysis of the local areas of the structure for studying the distribution of alloying elements were used. The energies of lattices of separate phases were also determined after the full-profile specification. All the lattices of the identified structures (about 30) turned out to be stable. It was established that in the Ti(49 at.%)–Al(49 at.%) systems under study with alloying additions of metals Ta, Y and Dy, there were intermetallides composed of AlTi3, TiAl in the hexagonal, tetragonal and triclinic units. It is known that after microalloying alloys by Y and Dy metals, the mass fraction of TiAl phases increases significantly (>70%).

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In this study the influence of scandium on the structural and phase state of the Ti-Al alloy obtained by the method of “Hydride Technology” (HT). The Rietveld method has allowed for determining the content of basic phases of the 49at.%Ti-49at.%Al-2at.%Sc system. By means of the methods of transmission electron microscopy (TEM) and X-ray spectral microanalysis, it has been established that scandium additives into the Ti-Al system result in the change of the quantitative content of phases in local regions of the structure. The Ti2Al5 phase has been found, and Ti2Al has been absent. In the morphology of substructures Ti-Al and Ti-Al-Sc there are lamellar structures or lamellae; the peculiarities of the distribution, fraction and size of which are influenced by scandium additives. The average width of Al-rich lamellae has been 0.85 µm, which is four times greater than that for the Ti-Al system (0.21 µm). For Ti-rich lamellae of the sample of the Ti-Al-Sc alloy, the average width of the lamellae has been 0.54 µm, and for Ti-Al it has been 0.34 µm. Based on the obtained data, a scheme of the distribution of phases in the composition of the Ti-Al-Sc alloy in the lamellar structures has been proposed. It has been established that in the Ti-Al-Sc system there is growth of the near-surface strength relative to Ti-Al. In this way, the microhardness of the Ti-Al-Sc alloy has amounted to 1.7 GPa, that is of the Ti-Al alloy which is 1.2 GPa.

Metal borides are widely used as heat-insulating materials, however, the range of their application in high-temperature conditions with oxidative medium is significantly restricted. To improve the thermal stability of structural materials based on titanium boride, and to prevent the growth of TiB 2 crystals, additives based on alumina-magnesia spinel with chemical resistant and refractory properties have been used. The aim of this work is to study the structure of TiB 2 with alumina-magnesia spinel additives obtained by self-propagating high-temperature synthesis (SHS). TiB 2 structure with uniform fine-grained distribution was obtained in an MgAl 2 O 4 matrix. The material composition was confirmed by X-ray diffraction analysis (DRON-3M, filtered Co kα-emission), FTIR spectroscopy (Thermo Electron Nicolet 5700, within the range of 1300-400 cm −1 ), and scanning electron microscopy (Philips SEM 515). The obtained material represents a composite, where the particles of TiB 2 with a size of 5 µm are uniformly distributed in the alloy of alumina-magnesia spinel.

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In this study, the influence of yttrium on the formation of the structural-phase state of the Ti-Al alloy, obtained by the “hydride technology” (GT) method, has been analyzed. Using transmission electron microscopy (TEM) and X-ray spectral microanalysis, the authors of the work have established the following phases formed in the sample volume and on the surface: Ti3Al, TiAl, Al, α-Ti, Ti3Al5, Y2Al, Y5Al3, YAl3, YAl, and Y6Ti4Al43. The lamellar structure has been formed in the alloy volume. The average width of the Al-rich lamellae was 0.36 µm and that of the Ti-rich lamellae was 0.21 µm. The formation of a triple Y6Ti4Al43 phase, which is localized along the boundaries of the lamellar structure, has been recorded. The localization scheme of the formed phases of the TAY alloy has been proposed.