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An isostatic hot-pressing technique for the fabrication of dense W samples' is presented. The samples’ microstructure and chemical content were analyzed. The most compact samples were received at 5 GPa pressure and 1500 and 2000 °C temperatures, with densities of 18.50 and 19.07 g/cm3, respectively. It has been established that high temperature exposure has a positive effect on both the microstructure and density. It is shown that as the sintering temperature increases, the porosity of the samples decreases from 32.31% to 0.94%, and their relative density increases from 67.69% to 99.06%. The crystal structure investigation revealed that all the samples contain the main body-centered cubic W phase, and the availability of the WO2 phase is observed just after the temperature of sintering increases above 1000 °C, which is confirmed by the appearance of 111 and 22-2 reflections. A study of the shielding effectiveness against gamma-radiation was carried out using the Phy-X/PSD software. A gamma-ray source of Co60 with energies of 0.8–2.5 MeV was applied for the calculations. The results were calculated for the sample with the highest density (19.07 g/cm3) and compared with the calculations for Pb. The W shielding effectiveness main parameters are determined: linear attenuation coefficient (at 0.8 MeV–1.46 cm-1), mean free path (at 2.5 MeV–1.2 cm) and half value layer (at 2.5 MeV–0.86 cm). These values turned out to be higher than for Pb, which makes shields based on W promising for use in the field of radiation protection.

Abstract This study announces the anomalous phase separation in CoNiP alloy electroplating. The observed phenomenon of the formation of magnetic bubbles was described for the first time for this triple CoNiP system. This study briefly covers all stages of magnetic bubble formation, starting from the formation of an amorphous phosphor-rich sublayer, followed by nucleation centers, and finally cobalt-rich bubbles. An explanation for the anomalous mechanism of bubble formation was found in the effects of additives and the phenomena of depolarization and superpolarization.

The W–Cu composites with nanosized grain boundaries and high effective density were fabricated using a new fast isostatic hot pressing method. A significantly faster method was proposed for the formation of W–Cu composites in comparison to the traditional ones. The influence of both the high temperature and pressure conditions on the microstructure, structure, chemical composition, and density values were observed. It has been shown that W–Cu samples have a polycrystalline well-packed microstructure. The copper performs the function of a matrix that surrounds the tungsten grains. The W–Cu composites have mixed bcc-W (sp. gr. Im 3¯ m) and fcc-Cu (sp. gr. Fm 3¯ m) phases. The W crystallite sizes vary from 107 to 175 nm depending on the sintering conditions. The optimal sintering regimes of the W–Cu composites with the highest density value of 16.37 g/cm3 were determined. Tungsten–copper composites with thicknesses of 0.06–0.27 cm have been fabricated for the radiation protection efficiency investigation against gamma rays. It has been shown that W–Cu samples have a high shielding efficiency from gamma radiation in the 0.276–1.25 MeV range of energies, which makes them excellent candidates as materials for radiation protection.