This work is devoted to the description and analysis of the technique used to obtain copper nanopowder by substance evaporation with the help of a powerful electron beam. The method possesses the...

In this study, Al₂₁Co₂₂Cr₂₂Fe₁₃Ni₂₂ high-entropy coatings were produced on steel substrates by non-vacuum electron beam cladding of Co, Cr, and NiAl powders. The high-temperature oxidation behavior of the coatings was studied by holding the specimens at 900 °C in air. The microstructure and phase constitution of the samples were studied both in the as-cladded state and after the heat treatment. The microstructure was characterized using light microscopy (LM) and scanning electron microscopy (SEM). Synchrotron X-ray diffraction (SXRD) and energy-dispersive X-ray spectroscopy (EDX) were used to study the phase constitution of the coatings and the “coating-substrate” interface. The coating consisted of disordered bcc (A2), ordered bcc (B2), and disordered fcc (A1) phases. Annealing the coatings for 50 h at 900 °C led to the formation of fcc precipitates in the bcc dendritic grains and a mixture of fcc and σ-phase particles in the interdendritic regions. Needle-like nanosized B2-precipitates were formed due to annealing in the fcc grains at the coating/substrate interface. The microhardness at the top of the as-cladded coating was 585 HV and gradually decreased towards the substrate. A more uniform distribution of the microhardness was obtained after the annealing. Its average value was 441 HV. Rhomboid Cr₂O₃, needle-like Al₂O₃, and spinels of a different morphology were found on the surface of the samples after oxidation at 900 °C.

This paper presents the results of a study on the morphology, structure, and luminescent properties of ceramics synthesized in the radiation field of MeWO₄ compositions (where Me is Mg, Ca, and Zn). The synthesis of ceramics was carried out by the direct action of the electron flux on an initial mixture of powders of the given stoichiometric composition. WO₃, ZnO, MgO, and CaO powders with particle sizes in the range of 1–50 microns were used for the synthesis of the samples. It was found that the yield of the radiation synthesis reaction (the ratio of the mass of the sample and the charge used), when treated with an electron flux with an energy of 1.4 MeV and a flux power density of 15–18 kW/cm², was in the range of 75–99%. The synthesis of all compositions was carried out under the same radiation treatment modes, although the melting temperatures of the starting materials varied significantly and ranged from 1473 °C (WO₃) to 2825 °C (MgO). The study of the ceramic structure showed that under the radiation effect of powerful radiation fluxes on the charge, a crystalline phase of the appropriate composition formed, regardless of the synthesis modes. The results of XRD studies show that during the radiation treatment of the charge, ceramics are formed mainly with the crystalline phases ZnWO₄, MgWO₄, and CaWO₄. These resulting MeWO₄ ceramics can be used for the same purposes as crystals. Photoluminescence (PL) and cathodoluminescence (CL) were studied under excitation using stationary ultraviolet radiation and nanosecond pulses of electron flux. In general, the PL and CL of synthesized ceramic samples ZnWO₄, MgWO₄, and CaWO₄ showed that their luminescent properties are similar to those of luminescence in corresponding crystalline materials. This indicates the formation of a crystalline phase in synthesized ceramic samples.