The paper presents the results obtained when studying material compositions of four samples of refractory copper-bearing ores from the Uzelga deposit along with technological solutions to improve their processing parameters. The refractoriness of ores is associated with a thin dissemination (up to a micron size) and close intergrowth of ore and rock minerals. Ferrous sulfides are represented by a wide range of minerals: pyrite, marcasite and their variety melnikovite, arsenic pyrite and arsenopyrite; sooty melnikovite has a higher flotation activity. The reduction of iron sulfides from 89 to 29 % is followed by a proportional increase of easy-floatable rock minerals to 45 % and clay to 9 %. These properties make these sulfides difficult to process (float) and maintain ore refractoriness. The content of copper sulfides in ore samples varies from 3,32 to 7,29 %; the relative fraction of copper sulfide in a form of tennantite in different deposit samples varies from 29 to 93 %. Copper is also present as chalcopyrite and bornite. The best flotation activity of tennantite can be seen in neutral and weak acid media in contrast with standard flotation mode for chalcopyrite and bornite with butyl xanthate in a high-alkaline calcareous medium. Free grains of copper minerals can be selectively extracted into the intermediate flotation copper concentrates when grinding maximum 60 % of the –71-μm class. The technology of flotation in a low-alkaline medium is developed for refractory copper-bearing ores with variable tennantite content using the M-TF selective sulfhydryl collector in intermediate copper flotations and copper concentrate upgrading cycle; aeration used to suppress melnikovite flotation activity makes it possible to achieve 80 % copper recovery into conditioned copper concentrate. Bornite, tennantite, chalcopyrite and sphalerite disseminated in pyrite make it rational to obtain copper-pyrite, copper-zinc-pyrite products with their yield up to 12 % for pyroand hydrometallurgical processing.

The article focuses on one of the important issues in rare and precious metals industry development – analytical control. It reviews the current state, importance, problems and prospects for analytical control development as an integral part of the rare and precious metal production and product quality assurance. Modern analytical control methods are described, namely atomic spectral, mass spectral, X-ray fluorescent and combined ones as well as their rational applications. It is shown that scientific and technological progress is inextricably linked with a drastic increase in the nomenclature of materials based on rare and precious metals and higher requirements for their quality. This will require creating new and improving existing analytical control methods, their standardization and metrological support. This work should involve research organizations in theRussianAcademy of Sciences, universities, industry research centers with research laboratories that have survived in the country after theSoviet Union dissolution, as well as promote plant research activities. It is necessary to effectively use the achievements of advanced analytical laboratories abroad, participate in international comparative tests. At the same time, special attention is paid to unsolved problems – scientifically justified statement of requirements for new types of products based on rare and precious metals; development and metrological assessment of sampling methods; development of high-quality metrological support for analytical control of rare and precious metal production; improvement of analytical methods; standardization of analytical methods; accreditation of analytical laboratories; training of highly qualified analytical chemists.

Regularities of the formation of ultrafine-grained (UFG) and submicrocrystalline (SMC) structures in new nickel-free low-modulus Ti–Nb–Mo–Zr titanium β alloys under the action of plastic deformation were studied. Temperature-time ranges of the development of dynamic recrystallization processes under the simultaneous action of temperature and plastic deformation were determined. The recrystallization diagram of II type of the Ti–28Nb–8Mo–12Zr alloy was constructed and analyzed. It was shown using scanning electron microscopy and electron backscatter diffraction method that the UFG structure with an average grain size of no more than 7 μm and high fraction of high-angle grain boundaries is formed in the investigated alloys as a result of longitudinal rolling followed by annealing for quenching. It was found that the formation of the UFG structure leads to a significant increase in the strength and plastic characteristics of these alloys. The regularities of the formation of UFG and SMC structures in the titanium β alloys Ti–28Nb–8Mo–12Zr and VT30 widely used in industry under the action of plastic deformation by the helical rolling method were studied. It was shown that the helical rolling of the VT30 alloy leads to the formation of the homogeneous UFG state as opposite to the developed Ti–28Nb–8Mo–12Zr β alloy where this method causes structure softening with micropores and microcracks formed in the central region. It is possible to form a nanostructured state with an average grain size of about 100 nm in Ti–Nb–Mo–Zr titanium β alloys using high-pressure torsion method.

The structure and magnetic properties of model high-cobalt WC–50%Co alloys with different carbon content and 1,6–5,6 wt.% TaC additives are studied. Model alloys are obtained by liquid-phase sintering of powder mixtures at 1420 °C, and their composition is described by the formula: 50%Co + 50%WC + xTaC + yC, where x = 0; 1,6; 2,6; 3,6; 4,6; 5,6 wt.%, y = 0; 0,2; 0,5 wt.%. It is shown that (Ta,W)C phase precipitates are present in all the investigated alloys, whereby at up to 3,6 wt.% TaC concentration the (Ta,W)C grains have a needle shape, and at ³3,6 wt.% TaC concentration the shape of the (Ta,W)C grains becomes spherical. (Ta,W)C phase precipitates are located both in the Co-binder and along the WC grain boundaries. The (Ta,W)C phase lattice parameter in low-carbon alloys lies in the range from 0,4438 nm for the 1,6 % TaC alloy up to 0,4451 nm for the 4,6 % TaC alloy. According to EDX analysis, the concentration of dissolved tungsten in the cobalt phase is independent of the TaC content and strongly depends on the total carbon content, and for alloys with high, elevated and low carbon content it is 7, 12 and 17 wt.%, respectively. TaC addition in alloys with a low and elevated carbon content leads to an increase in coercive force by 875 A/m and a decrease in magnetic saturation by 5–10 Gs·m3/g. The experimental results allowed putting forward a hypothesis about the possibility of forming dispersed tantalumcontaining precipitates in the binder phase.

Al–Cu–Mn (Zr) alloys feature high strength and processability without any thermal treatment operations. Al–2%Cu–1,5%Mn–2%B and Al–2%Cu–1,5%Mn–0,4%Zr–2%B alloys were obtained in order to investigate the possibility of producing a aluminum boroncontaining alloy in the form of high-strength sheet rolled stock without thermal treatment. Melting was performed in the RELTEK induction furnace with intense melt stirring to eliminate sedimentation of boride refractory particles. Melting temperature was 950– 1000 °С. Melt was poured into 40×120×200 mm graphite casting molds. Calculation methods (Thermo-Calc) were used to demonstrate that manganese forms complex borides with aluminum and zirconium at a melting temperature while there is enough manganese in liquid and there is practically no zirconium left. Experimental methods (electronic scanning microscopy and electron microprobe analysis) proved the formation of the complex AlB₂Mn₂ boride, however, manganese remained in a solid solution is enough to form the Al₂₀Cu₂Mn₃ phase particles in the amount up to 7 wt.%. In the alloy with zirconium, boron stimulates primary Al₃Zr crystal separation and, therefore, zirconium content left in the aluminum solid solution is not sufficient for hardening. It is shown that it is possible to produce thin-rolled steel with a thickness of less than 0,3 mm with uniformly distributed clusters of the boride phase with a particle size of less than 10 μm. A high level of strength up to 543 MPa is reached without the use of hardening and aging due to the precipitation of Al₂₀Cu₂Mn₃ phase dispersions during hot deformation (t =450 °C).

The article presents experimental data on explosive compaction of chromium carbide (Cr3C2) powder mixtures with metals (Ti, Ni, Cu) provided with theoretical explanations. These data were used as a basis for stating science-based principles of composition selection and technology development to produce antifriction wear-resistant chromium carbide hard alloys and coatings by explosion. Explosive compaction of powder mixtures was carried out according to a scheme using a normally incident plane detonation wave in a wide range of loading parameters (powder heating temperature in shock waves varied from 200 to1000 °Cand maximum shock compression pressure varied from 4 to 16 GPa during experiments). Phase transformation analysis was carried out by the numerical thermodynamic modeling of phase equilibrium using the Thermo-Calc software. Microstructure, chemical and phase compositions were studied using optical («Axiovert 40МАТ» by CarlZeiss,Germany), scanning («Versa 3D» and «Quanta 3D FEG» byFEI,USA), transmission («BS 540» byTesla,Czech Republic, «Titan 80-300» and «Tecnai G2 20F» byFEI,USA) electron microscopes and «Solver Pro» atomic force microscope (LLC «NT-MDT», Zelenograd). Temperature stability and oxidation resistance at elevated temperatures of the materials obtained by explosion was studied using thermogravimetric analysis (TGA) using the «STA 449 F3 Jupiter» instrument (NETZSCH, Germany) in the synthetic air environment when heated to1500 °C. Tribological tests were carried out on the MI-1M friction machine (MEZIMiV,Moscow) according to the pin-on-ring scheme with plunging in distilled water environment. The mechanisms of consolidation and formation of strong boundaries between powder material particles during explosive compaction are described. It is shown that hard alloys of chromium carbide with titanium bond obtained by explosion retain their phase compositions without any changes and resist to oxidation up to600 °C, and also have significantly better anti-friction properties and wear resistance than the SGP-0,5 and KHN-20 materials used in water-lubricated friction couples until the present time.

OJSC «Kompozit» traces its history back to the Central Research Institute of Materials Science (CRIMS) and successfully acts as a leading material science institute in the rocket and space industry up to the present day. The enterprise uses and improves state-of-theart technologies, and creates a variety of new metal, non-metallic, composite and ceramic materials. This article provides an overview of powder sector development from the metallurgy of granules to additive technologies and shows the participation of MISIS graduates. The experience of OJSC «Kompozit» in the manufacturing of parts by selective electron beam melting (SEBM) of home-made VT6S titanium alloy powders. Initial powders are obtained by plasma centrifugal spraying of the bar stock. It is shown that the powders feature an ideal spherical shape, low defect rate, high processability and fully meet the process requirements. The microstructure and properties of samples and parts obtained by the SEBM are studied.