Li Xiang-Min, Shi Zhang-Zhi, Zhang Jia-You, Zhou Chao, Wang Lu-Ning
Beijing Advanced Innovation Center for Materials Genome Engineering, State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, PR China.
Beijing Advanced Innovation Center for Materials Genome Engineering, State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, PR China; Institute of Materials Intelligent Technology, Liaoning Academy of Materials, Shenyang 110004, China.
Acta Biomater. 2025 Jan 24;193:584-603. doi: 10.1016/j.actbio.2024.12.050. Epub 2024 Dec 20.
Strain softening is a common issue for high-strength biodegradable Zn alloys. We developed Zn-0.6Mn-0.05Mg-0.05Ca alloy with a bimodal grain structure by extrusion and caliber rolling, refer to as ZMMC063 (CRD). The alloy exhibits the best strength-ductility synergy among Zn-Mn based alloys, which shows a yield strength of 386 MPa, an ultimate tensile strength of 443 MPa, and an elongation rate of 31%. This is the first 380 MPa-30% grade Zn-Mn based alloy, surpassing the previous reported Zn alloy with 320 MPa-20% grade. Its work-hardening strain reaches as high as 11.6%, which is 4 times greater than that of other 300 MPa Zn-Mn based alloys. This is owing to hetero-deformation induced strengthening effect of the bimodal grain. Additionally, it demonstrates for the first time that micro-galvanic corrosion happens between coarse and fine Zn grains, thereby accelerating degradation of the alloy. This provides a feasible protocol for controlling degradation of Zn alloys. Compared with the extruded Zn-0.6Mn-0.05Mg-0.05Ca alloy, refer to as ZMMC063 (HE), the increased release of Mg and Ca ions in ZMMC063 (CRD) improves tolerance of MC3T3-E1 cells to Zn. Consequently, ZMMC063 (CRD) shows higher antibacterial abilities against E. coli and S. aureus, meanwhile much less toxicity to MC3T3-E1 cells. Synergistic effect of Zn, Mg and Ca ions promote expression of ALP, COl-1, OCN and Runx-2, so that ZMMC063 (CRD) exhibits better ability to induce osteogenic differentiation. This paper suggests that ZMMC063 (CRD) is a promising candidate for orthopedic implants. STATEMENT OF SIGNIFICANCE: Previously the highest yield strength-elongation level of Zn-Mn based alloys is 320 MPa-20% grade. At such a high strength, the alloys' work-hardening strain (Ewh) values are below 4%. To further improve comprehensive properties of Zn-Mn based alloys, 380 MPa-30% grade Zn-0.6Mn-0.05Mg-0.05Ca alloy with bimodal grain structure is developed by extrusion and caliber rolling. The alloy's Ewh reaches as high as 11.6%, due to the hetero-deformation induced effect of bimodal grain structure. Additionally, micro-galvanic corrosion happens between bimodal grains, which accelerates the alloy's degradation. In vitro studies show that the alloy exhibits enhanced antibacterial activity, good cytocompatibility, and promising osteogenic effect, indicating that it is a promising candidate for orthopedic implants.
应变软化是高强度可生物降解锌合金的常见问题。我们通过挤压和定径轧制开发了具有双峰晶粒结构的Zn-0.6Mn-0.05Mg-0.05Ca合金，称为ZMMC063（CRD）。该合金在锌锰基合金中表现出最佳的强度-延展性协同效应，其屈服强度为386MPa，极限抗拉强度为443MPa，伸长率为31%。这是首个380MPa-30%级别的锌锰基合金，超过了先前报道的320MPa-20%级别的锌合金。其加工硬化应变高达11.6%，是其他300MPa锌锰基合金的4倍。这归因于双峰晶粒的异质变形诱导强化效应。此外，首次证明了粗、细锌晶粒之间发生微电偶腐蚀，从而加速了合金的降解。这为控制锌合金的降解提供了一种可行的方案。与挤压态的Zn-0.6Mn-0.05Mg-0.05Ca合金（称为ZMMC063（HE））相比，ZMMC063（CRD）中镁和钙离子释放量的增加提高了MC3T3-E1细胞对锌的耐受性。因此，ZMMC063（CRD）对大肠杆菌和金黄色葡萄球菌表现出更高的抗菌能力，同时对MC3T3-E1细胞的毒性要小得多。锌、镁和钙离子的协同作用促进了碱性磷酸酶、I型胶原蛋白、骨钙素和Runx-2的表达，因此ZMMC063（CRD）表现出更好的诱导成骨分化的能力。本文表明ZMMC063（CRD）是一种有前途的骨科植入物候选材料。重要意义声明：此前锌锰基合金的最高屈服强度-伸长率水平为320MPa-20%级别。在如此高的强度下，合金的加工硬化应变（Ewh）值低于4%。为了进一步提高锌锰基合金的综合性能，通过挤压和定径轧制开发了具有双峰晶粒结构的380MPa-30%级别的Zn-0.6Mn-0.05Mg-0.05Ca合金。由于双峰晶粒结构的异质变形诱导效应，该合金的Ewh高达11.6%。此外，双峰晶粒之间发生微电偶腐蚀，加速了合金的降解。体外研究表明，该合金具有增强的抗菌活性、良好的细胞相容性和有前景的成骨效果，表明它是一种有前途的骨科植入物候选材料。
