Evolution of microstructure, electromagnetic shielding, and in vitro corrosion properties of Mg-Ni composites for cancer biomarker applications

The heavily deformed composites are increasingly used in various applications such as nuclear power plants, medical, cancer biomarker, and aerospace industries. This research investigates the effect of rolling strain, reinforcing layer thickness, and layer stacking on microstructure, grain refinement, hardness, shielding effectiveness, and in vitro corrosion and degradation properties of Ni/Mg/Ni and Mg/Ni/Mg multilayered composites. The composites were produced by seven passes of the accumulative roll bonding (ARB) process at room temperature. The microstructural characterization showed the grain refinement in all layers. By increasing the thickness of reinforcing layers, the grain sizes of the inner layers decreased although the outer layers showed finer grains. The outer layers in composites also indicated higher hardness than the inner layers. The maximum hardness of the Mg layer in Mg/Ni/Mg and Ni/Mg/Ni was 85 and 77 HV while the maximum hardness of the Ni layer in Mg/Ni/Mg and Ni/Mg/Ni was 161 and 164 HV. In addition, the Ni/Mg/Ni composites with 57 dB showed better electromagnetic interference shielding effectiveness than Mg/Ni/Mg composites with 44 dB. Furthermore, the mass attenuation coefficient of gamma rays of composites grew at higher rolling strains. The attenuation coefficients of composites were respectively 0.12 and 0.088 cm²/g for Ni/Mg/Ni and Mg/Ni/Mg composites after the final pass. Also, based on the results of in vitro corrosion and degradation, Ni/Mg/Ni and Mg/Ni/Mg composites revealed adverse behaviors versus rolling strain and thickness of the inner layer. The Ni/Mg/Ni composite showed maximum corrosion resistance and minimum degradation rate after the first pass with the thinnest Mg layer while the Mg/Ni/Mg composite showed maximum corrosion potential and minimum degradation rate after the final pass with the thickest Ni layer.