Heavy alloy based on tungsten and bismuth: fabrication, crystal structure, morphology, and shielding efficiency against gamma-radiation

Abstract

W–Bi₂O₃ composites were fabricated using the hot isostatic pressing technique for the first time. The duration of the samples sintering was 3 minutes under conditions of high pressure and temperature. The study of microstructural features and chemical composition of sintered samples was carried out using scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The effect of temperature on the quality of the obtained W–Bi₂O₃ composites is determined. The densest samples were obtained at a pressure of 5 GPa and temperatures of 25 °C and 500 °C, the densities of which were 18.10 and 17.85 g cm⁻³, respectively. It is presented that high temperature exposure during sintering adversely affects both the composite density and microstructure due to the redox reaction accompanied by the reduction of Bi and the oxidation of W. The results of the W–Bi₂O₃ structure study using X-ray diffraction analysis showed that all samples included the main bulk-centered cubic W phase. The presence of the WO₂ phase is noted only when the sintering temperature is increased up to 850 °C, which is confirmed by the appearance of diffraction peaks that correspond to 111 and 22−2 crystallographic planes. The shielding efficiency of the W–Bi₂O₃ composite against gamma radiation using the Phy-X/PSD software was evaluated. A Co⁶⁰ isotope with an energy of 0.826–2.506 MeV was used as a source of gamma radiation. The calculation results were compared with those for Pb and Bi. Key shielding parameters such as the linear attenuation coefficient, half-value layer, tenth-value layer, mean free path, and effective atomic number are determined. The calculation results revealed that the W–Bi₂O₃ composite surpasses Pb and Bi in its shielding properties, which makes it promising for use as a prospective material for radiation shielding applications.