Elevated electrochemical corrosion behavior of a B ₄ C/Al neutron absorber by shot peening modification

Abstract The shot peening (SP) method was employed to modify the surface properties of 33% B ₄ C/Al composites. The microhardness, morphology, and corrosion behavior of B ₄ C/Al composites were characterized by using the Vickers hardness test, scanning electron microscopy, potential dynamic scanning, and electrochemical impedance spectroscopy. The experimental observations revealed that the B ₄ C particles were embedded into the matrix, which rendered the plastic deformation of Al alloy near the surface of B ₄ C/Al composites on the condition of the high-speed impact of projectiles. As such, the density and hardness of the B ₄ C/Al composite modified layer near the surface were enhanced. After the SP treatment, the results of the electrochemical polarization curve test showed that the corrosion potential increased by 55.2 mV, the corrosion current changed from 3.828×10 ^-6 to 1.102×10 ^-6 A/cm ² , and the corrosion rate decreased by 72.2%, respectively. This indicates that the corrosion resistance significantly improved via the SP treatment. The mechanism of the formation of Al alloy modified layer and electrochemical corrosion behaviors is discussed in detail.