Effects of trace amounts of lithium on the microstructure, mechanical properties, corrosion behavior, antibacterial activity and biocompatibility of Zn–Cu alloy

To investigate the effects of adding trace amounts of Li on the microstructure, mechanical properties, corrosion behavior, antibacterial activity and biocompatibility of the Zn–Cu alloy, Zn–1.2Cu, Zn–1.2Cu–0.02Li as well as Zn–0.02Li (as a reference) alloys were prepared in this work. The results showed that the grain size of the as-cast Zn–1.2Cu–0.02Li alloy is significantly smaller than that of the Zn–1.2Cu alloy, suggesting a notable effect of the trace amounts of Li on the grain refinement. Moreover, a bimodal structure was formed in both the hot-extruded Zn–1.2Cu and Zn–1.2Cu–0.02Li alloys due to the precipitation of submicron-sized ɛ-CuZn4 particles. However, the latter has a much higher volume fraction of submicron-sized ɛ-CuZn4 particles than the former. Furthermore, nano-sized ɛ-CuZn4 particles precipitate from the matrix of the fine-grained region in the latter alloy. The hot-extruded Zn–1.2Cu–0.02Li alloy exhibits a yield strength (YS) of 278 ± 3 MPa and ultimate tensile strength (UTS) of 320 ± 1 MPa, which are 76