Investigation of nuclear radiation shielding properties of new type high entropy composite materials with oxide and nitride additives

Radiation shielding, one of the methods for protecting against the harmful effects of ionizing radiation, has become a field that has attracted the attention of researchers in recent years. The type and energy of radiation must be taken into account when producing an effective shielding material. X-rays and gamma rays can be effectively attenuated by high-density materials, while neutrons can be effectively attenuated by lightweight materials with high hydrogen content. Within the scope of this thesis, two different high-entropy alloys based on Hf–Ti–Al–Cu–Ni and Mo–Ti–Al–Cu–Ni were produced. Furthermore, composite samples were prepared by reinforcing these alloys with WO₃, Er₂O₃, Ta₂O₅, Bi₂O₃, TiN, ZrN, CrN, and BN compounds at different additive ratios. Radiation shielding properties of the produced samples were determined experimentally with Ultra-Ge detector using gamma rays with energies of 81, 160, 276, 302, 356 and 383 keV emitted from Barium-133 radioactive source. These parameters include mass reduction coefficient (µ/ρ,(cm^2)/g), linear reduction coefficient, half-value thickness (Δ_0.5), effective atomic number (Zeff), electron density (Nel). The same parameters were calculated theoretically using the EpiXS program. The experimental and theoretical results were compared, and the experimental neutron shielding properties of the investigated composite materials were evaluated by calculating the theoretical fast neutron reduction cross section (ΣR) parameters. In addition, the buildup factors (EBF and EABF) for the materials produced in this study were calculated theoretically using the EpiXS program. In conclusion, it has been shown experimentally and theoretically that the oxide and nitride doped high entropy alloys produced in this study, especially the Bi₂O₃, WO₃ and ZrN/BN reinforced composites, exhibit superior shielding performance against both gamma rays and fast neutrons.