Obtention of WCuNi composite material using powder metallurgy for gamma (γ) radiation attenuation

Abstract

This work aimed to obtain a composite material WCuNi using the powder metallurgy. This composite is usable as material for the attenuation of gamma radiation (γ). The tungsten (W) is the main shielding element in this composite. The tungsten has high density (19.25 g.cm-3), high melting point (3,422 °C) and is presented as matrix of the composite. In order to meet the need for sintering with temperatures below 1,200 °C, the liquid phase sintering technique was used. For preparation of the samples, shape and size of the particles of the metal powders were analyzed. With the intention of homogenize the distribution of the metallic powders and to reduce the average particle size, a ball mill was used for 24 hours. After grinding, the particle size analysis showed that the mean particle size in WCuNi composition was 12 μm. The powder mixture was compacted in isostatic press at 200 MPa pressure. The samples were sintered at 1,100 °C and at 2,100 mbar pressure of reducing atmosphere (H2) for 8 hours. The formation of the isomorphic system CuNi is responsible for giving the mechanical characteristic of solid to the composite WCuNi. Optical and electronic microscopy (SEM) with EDS were undertaken to characterize the samples. The classical scientific method of experimentations with gamma radiation of the cobalt-60 source by attenuation of the energies was employed to study the effects on the samples. For the energies of 1,173 MeV and 1,332MeV the experimental method indicated the necessity of 11.95 mm of thickness for the solid compound W8Cu1Ni with the obtained density of 11.46 g.cm-3 to attenuate the energy to level allowed for occupationally exposed persons. The experimental values obtained were compared with values calculated by XCOM software database (NIST) of 12.45 mm and convergence of values was observed.