Influence of Surface Nanocrystallization on Aluminizing Behavior of AZ91D Magnesium Alloy

Surface aluminizing for magnesium alloy is an effective method to improve corrosion resistance. This research introduced surface nanocrystallization as the pre-process of aluminizing. AZ91D magnesium alloy was processed by high energy shot peening (HESP) to achieve surface nanocrystallization, and then vacuum solid state aluminum diffusion was performed to obtain aluminized layer. The morphology of the aluminized layer was observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that the surface of the nanocrystalline with grain size of 100 nm is obtained after HESP of AZ91D magnesium alloy. The depth of the HESPed aluminized layer is thicker than that of the aluminized layer without HESP. After 440 degrees C/12 h diffusion, the depth of aluminized layer increases to 70 gm. The corrosion resistance of AZ91D magnesium alloys were characterized by electrochemical method. It is shown that the aluminized layer obviously lowers the corrosion rate of AZ91D magnesium alloy. Therefore, high energy shot peening (HESP) is beneficial to surface aluminizing and can improve the corrosion resistance of magnesium alloy.