Additively manufactured biodegradable Zn-Mn-based implants with an unprecedented balance of strength and ductility

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作   者：

Huang, Chengcong;  Wang, Yizhu;  Yang, Fan;  Shi, Yixuan;  Zhao, Shangyan;  Li, Xuan;  Lu, Yuchen;  Wu, Yuzhi;  Zhou, Jie;  Zadpoor, Amir A.;  Xu, Wei;  Li, Yageng;  Wang, Luning; 

作者机构：

Delft University of Technology BioMechanical Engineering;  University of Science and Technology Beijing Institute of Engineering and Technology;  University of Science and Technology Beijing School of Materials Science and Engineering;  Peking Univ Third Hosp; 

关键词：

Laser powder bed fusion;  Biodegradation behavior;  Mechanical properties;  Biocompatibility;  Additive manufacturing;  Zinc alloy; 

期刊名称：

Acta biomaterialia

i s s n：

1742-7061

年卷期：

2025 年 196 卷

页   码：

506-522

页   码：

摘   要：

Additively manufactured (AM) biodegradable zinc alloys hold huge potential as promising candidates for bone defect and fracture repair, thanks to their suitable biodegradation rates and acceptable biocompatibility. However, the mechanical properties of AM zinc alloys developed so far, ductility in particular, fall short of the requirements for bone substitution. Here, we present Zn-1Mn and Zn-1Mn-0.4Mg alloy implants with unique microstructures, fabricated using laser powder bed fusion (LPBF). Notably, the LPBF Zn-Mn-Mg alloy exhibited an extraordinary balance of strength and ductility, with an ultimate tensile strength of 289 MPa, yield strength of 213.5 MPa, and elongation over 20 %, outperforming all previously reported AM zinc alloys. The simultaneously enhanced strength and ductility of the ternary alloy were attributed to the strong grain-refining effect of the Mg2Zn11 second phase and the synthetic strengthening caused by the dispersion of the MnZn13 and Mg2Zn11 second phases inside the grains and at the grain boundaries. In addition, both alloys had similar rates of in vitro biodegradation (similar to 0.15 mm/year), properly aligned with the bone remodeling process, while also demonstrating favorable biocompatibility and upregulating multiple osteogenic markers. The Zn-Mn-Mg alloy showed even better osteogenic potential than the Zn-Mn alloy, owing to the addition of Mg. The combined attributes of the LPBF Zn-Mn-Mg ternary alloy indicated huge potential for its use as a bone repair material, especially for loadbearing bone fixation.Statement of significance: The mechanical properties of previously developed additively manufactured biodegradable zinc alloys, especially ductility, have not met the requirements for bone repair. Using laser powder bed fusion (LPBF), we fabricated Zn-1Mn and Zn-1Mn-0.4Mg alloy implants with unique microstructures. The LPBF Zn-Mn-Mg alloy demonstrated an exceptional balance of strength and ductility, achieving a tensile strength of 289 MPa, yield strength of 213.5 MPa, and elongation over 20 %, surpassing all reported AM zinc alloys. This study is the first to produce a directly printed biodegradable alloy meeting the mechanical requirements for bone fixation devices without post-processing. Additionally, the alloy exhibited moderate a biodegradation rate and excellent biocompatibility, underscoring its potential for load-bearing bone repair applications.