Quasi-continuous-wave laser surface melting of aluminium alloy: Precipitate morphology, solute segregation and corrosion resistance

Abstract A quasi-continuous-wave laser surface melting is performed on 2219 aluminium alloys to improve the corrosion resistance. The fast cooling rate and the multi-directional solidification behavior of the process transform large and long-chained constituent particles into fine and isolated circular precipitates with alleviated solute segregation. The improved corrosion resistance is due to the formation of low-flaw-density passive film, the reduction of the driving force for corrosion and the improvement of the re-passivation capability of the modified surface. The large and long-chained constituent particles are the preferred sites for corrosion initiation and propagation.