Three-stage degradation behavior and dealloying assisted galvanic corrosion mechanism of 300 MPa grade Zn-2Cu-xLi (x = 0.2-0.8) alloys in simulated body fluid

Abstract

Corrosion behaviors of biodegradable Zn alloys with ternary phases are rarely studied. This paper reveals three-stage corrosion behavior of high-strength Zn-2Cu-(0.2–0.8)Li alloys immersed in simulated body fluid for 30 days. At stage Ⅰ, Zn phase is preferentially corroded due to cathodic Zn-Cu-Li ternary phases recently identified. At stage Ⅱ, corrosion is suppressed due to formation of protective layer containing LiOH and Li2CO3 with appropriate Pilling-Bedworth ratios. At stage Ⅲ, dealloying of Zn-Cu-Li phases rises their Cu contents, accelerating galvanic corrosion and resulting in large pits beyond 200 µm.