Magnesium alloys, hailed as the "green engineering material of the 21st century," have broad application prospects in aerospace, communications, and biomedical fields. However, due to their inherently active chemical nature, magnesium alloys are prone to corrosion in corrosive environments, especially pronounced at weld seams, severely hindering their widespread application .
The research team compared the corrosion resistance of AZ31B magnesium alloy base material, welds without carbon nanotubes, and welds with added carbon nanotubes. The results showed that the introduction of carbon nanotubes effectively refined the weld grains, weakened the texture orientation, and improved microstructural uniformity. After adding carbon nanotubes, both the hydrogen evolution corrosion rate and the weight loss corrosion rate of the welds decreased by more than 30%, and the density of corrosion products significantly increased .
Electrochemical tests further confirmed this breakthrough: the corrosion current density of welds with added carbon nanotubes was 1.220 μA/cm², with a polarization resistance of 7155 Ω·cm²; in contrast, welds without carbon nanotubes exhibited a corrosion current density of 2.480 μA/cm² and a polarization resistance of only about 269.5 Ω·cm² . The study also found that the addition of carbon nanotubes increased the precipitated phase content in the welds from 0.60% to 1.76%. These precipitated phases release Al³⁺ during the corrosion process, promoting the formation of a dense Al₂O₃ passive film, effectively preventing further erosion of the metal matrix by corrosive media.
This research achievement provides an important scientific basis and technical support for the industrial application of magnesium alloys in corrosive environments.