Fatigue behavior of biodegradable Zn-Li binary alloys in air and simulated body fluid with pure Zn as control

Zn-Li-based alloys have drawn great attention as promising candidates for load-bearing sites, such as intramedullary nails and bone plates. They possess high monotonic strength (over 500MPa) and better pitting resistance with lithium-rich layers acting as barriers for corrosion attack under (quasi-)static conditions. However, their response to dynamic loadings such as fatigue is still unknown. Herein, the corrosion fatigue behavior of a series of Zn-Li binary alloys with different lithium addition amounts was tested in simulated body fluid. Tensile and fatigue strength of the materials were proportional to lithium content while corrosion fatigue strength was not. Extremely long cracks that extended parallel to the loading direction were found in Zn-1.0wt.%Li alloys. These cracks propagated by selective dissolution of the lithium-rich phase in the eutectoid regions and drastically reduced the corrosion fatigue strength of Zn-1.0wt.%Li alloy owing to exacerbated crack propagation. To sum up, Zn-Li binary alloys showed fatigue strength comparable to pure iron and pure titanium, which confirmed their loading capacity under dynamic conditions.

Automated summary

Zn-Li-based alloys have high monotonic strength and better pitting resistance, but their response to dynamic loadings is still unknown. The corrosion fatigue behavior of Zn-Li binary alloys with different lithium addition amounts was tested, and it was found that the corrosion fatigue strength was not proportional to lithium content. Zn-Li binary alloys showed comparable fatigue strength to pure iron and pure titanium, confirming their loading capacity under dynamic conditions.