Suppression mechanism of initial pitting corrosion of pure Zn by Li alloying

Abstract Localized corrosion makes Zn vulnerable to unpredictable fracture under stress loading, resulting in mechanical failure when used as implants in human body. This study reveals that 0.8 wt.% Li alloying suppresses pitting corrosion of Zn significantly in simulated body fluid, resulting in 290 times less of localized corrosion volume after immersion for 30 days. A corrosion layer with two sub-layers forms on the alloy surface. The 10-nm-thick inner layer consists of amorphous Li2O/LiOH and ZnO/Zn(OH)2, while the 55-nm-thick outer sub-layer consists of Li2CO3 polycrystals, which is very effective to suppress pitting corrosion by blocking chloride ion penetration.