Strong modification of double-pulsed femtosecond laser to reinforce anticorrosion of Al alloy surface

Abstract

Aiming at the uncertainties and limitations in the laser modification of material surfaces for the corrosion protection, we here exploit a method of double-pulsed femtosecond laser processing with variable picosecond time delays, to effectively reinforce the anticorrosion performance of aluminum alloys. Compared with the traditional single-beam femtosecond laser irradiation, the adoption of double-pulsed laser irradiation especially with the optimal time delay of 50 ps, can decrease about 16 times in the magnitude of the corrosion current density, associated with the increase by 77.8 mV and 23 times in the corrosion potential and the impedance, respectively. The comprehensive insight analyses reveal that such an enhanced anticorrosion phenomenon is originated from the strong modification of the chemical and phase compositions on the metal surface, thus resulting in the higher degree of in-situ material oxidation with a prominent feature of the amorphous state, which can be evidenced not only in the shallow outer-layer surface but also extending to the deep inner-layer region. The significant roles of these laser modifications can be well elucidated by the proposed scenario.