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 x 10(15) ions/cm(2). 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.