Corrosion properties and morphology of laser melted aluminum alloy 8022 surface

Laser surface melting of aluminum alloy 8022 is considered and electrochemical studies of the laser-melted and as-received alloy surface are carried out. The surface morphology and metallurgical changes in the laser-melted region are examined using optical microscopy, electron scanning microscopy (SEM), and atomic force microscopy (AFM). Elemental changes in the specimens after the laser-melting process are examined using energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD) is used for assessment of the compound formed after the laser-treatment process. Nitrogen is used as an assisting gas during the laser-melting process to prevent high-temperature oxidation reactions. It is found that the laser-melted surfaces is free from cracks and deep cavities. The oxygen diffusion in the surface region of the melt layer forms Al ₂O ₃ compound in the surface vicinity. The corrosion current increases significantly for the laser-melted specimens due to the irregular surface structure. AC impedance results showed a decrease in pores resistant and an increase in pores capacitance. In addition, the surface morphology resulting from the laser melting gives rise to pitting sites at the surface.