Influence of carbon ion implantation energy on aluminum carbide precipitation and electrochemical corrosion resistance of aluminum

The effects of varying carbon ions (C⁺) implantation energies on Aluminum Carbide (Al₄C₃) precipitation, surface morphology and electrochemical corrosion resistance of aluminum (Al) were evaluated. The Al samples were implanted with C⁺ of different energies of 0.25, 0.5, 1, 2, and 4 MeV at a constant dose of 1 × 10¹⁵ ions/cm². The X-rays diffraction (XRD) and field emission scanning electron microscope (FESEM) results showed Al₄C₃ precipitates in the ion-implanted Al which were decreased at higher implantation energies (≥1 MeV). The decrease in Al₄C₃ precipitation was attributed to the lower chemical reactivity of C⁺ with Al due to ion-induced lattice defects. The Al surface became rough, and micro-cracks appeared on it as the ion energy increased above 0.25 MeV. The electrochemical corrosion rate of Al decreased from 469.9 mpy to 70.32 mpy after C⁺ implantation at 0.25 MeV. However, the corrosion rate increased with increasing ion energy above 0.25 MeV. This changes in corrosion rate were elucidated on the basis of Al₄C₃ precipitation and lattice defects in Al created by C⁺ implantation. The SEM analysis of electrochemically tested samples indicated lower pitting in the sample implanted with 0.25 MeV ions as compared to those implanted with higher energy.