Synthesis, mechanical properties, and in vitro corrosion behavior of biodegradable Zn–Li–Cu alloys

Abstract

Zinc alloys are proposed as suitable biodegradable materials due to an intermediate corrosion rate, non-toxicity, and good mechanical properties. The novel ternary Zn–Li–Cu alloy system is explored in this study as a potential biodegradable material for stent and other temporary medical device applications, utilizing pure Zn, Zn–Li, and Zn–Cu as control materials. After casting and hot-rolling, the chemistry, microstructure, mechanical properties, and immersion corrosion behavior of Zn-0.3Li-xCu (x = 2, 3.5, and 5 wt%) are investigated. The simulated Zn–Li–Cu ternary phase diagram compares well with experimental chemistry and phase fractions. Zn–Li–Cu alloys demonstrated excellent ultimate tensile strength (333–428 MPa) and hardness (125–134HV), with acceptable elongation (18–26%) compared to general stent design criteria and similar materials. In vitro corrosion rates of approximately 0.01 mm yr−1 were observed after 21 days of immersion in Hank’s Balanced Salt Solution (HBSS), where depletion of metal ions is slowed by the formation of a dense corrosion product layer that partially breaks down after 100 days. The current study highlights that the novel Zn–Li–Cu alloys are promising candidates for medical device applications by exceeding stent design criteria.