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

Guannan Li; Dafu Chen; Yoji Mine; Kazuki Takashima; Yufeng Zheng

doi:10.1016/j.actbio.2023.07.030

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

Acta Biomater. 2023 Sep 15:168:637-649. doi: 10.1016/j.actbio.2023.07.030. Epub 2023 Jul 28.

Authors

Guannan Li¹, Dafu Chen², Yoji Mine³, Kazuki Takashima³, Yufeng Zheng⁴

Affiliations

¹ School of Materials Science and Engineering, Peking University, Beijing, 100871, China.
² Laboratory of Bone Tissue Engineering, Beijing Research Institute of Traumatology and Orthopaedics, Beijing JiShuiTan Hospital, Beijing 100035, China. Electronic address: chendafujst@126.com.
³ Department of Materials Science and Engineering, Kumamoto University, 2-39-1 Kurokami, Chuo-ku, Kumamoto 860-8555, Japan.
⁴ School of Materials Science and Engineering, Peking University, Beijing, 100871, China. Electronic address: yfzheng@pku.edu.cn.

PMID: 37517618
DOI: 10.1016/j.actbio.2023.07.030

Abstract

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. STATEMENT OF SIGNIFICANCE: Zn-Li-based alloys are qualified as biodegradable metals and are dedicated to load-bearing applications. Current research has shown that lithium can suppress pitting corrosion by the formation of lithium-rich layers on the alloy surface during (quasi-)static conditions. However, how these materials respond to dynamic loading is still unknown. The present study investigated the influence of lithium amount (0.1∼1.0wt.%) on the corrosion fatigue behavior of binary Zn-Li alloys. The results showed that lithium effectively improved the mechanical strength but can harm corrosion fatigue strength at high content due to selective dissolution of lithium-rich phase. This demonstrated that the amount of lithium should be controlled for optimal properties. Zn-0.8wt.%Li alloy demonstrated a good combination of tensile and corrosion fatigue strength, which can be further improved by proper alloying and thermomechanical treatment.

Keywords: Air; Biodegradable metals; Corrosion fatigue; Simulated body fluid; Zn-Li alloys.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Absorbable Implants
Alloys*
Biocompatible Materials
Body Fluids*
Bone Plates
Corrosion
Lithium
Materials Testing
Zinc

Substances

Alloys
Lithium
Zinc
Biocompatible Materials