新一代可降解血管支架用锌合金相关材料学问题基础研究

锌合金因具有良好生物相容性和适宜降解速率，有望成为新一代可降解血管支架的理想材料，但临床应用面临着“老化”和“加工硬化能力弱”的材料学瓶颈问题。本申请拟在新研发的医用抗老化Zn-Cu二元合金基础上，借助第一性原理计算对Zn-Cu合金进行进一步成分设计，引入固溶原子和第二相粒子提高Zn-Cu系合金基体热稳定性和再结晶温度；调控挤压加工和热处理工艺，构建有利于强度和塑性匹配的双峰组织。以此促进锌合金基体中非基面位错开动，提升位错之间、位错与晶界、位错与固溶原子和第二相之间交互作用，从而实现抗老化和加工硬化能力；研究锌合金的降解行为，揭示显微组织与腐蚀和腐蚀疲劳行为之间的关系规律。通过宏微观分析和计算模拟，解析新型Zn-Cu系合金抗老化和加工硬化能力的机理，建立“合金设计-变形加工工艺-微观组织-力学与降解行为”之间的构效关系，为血管支架用高性能锌合金设计研发和临床应用奠定材料学理论和技术基础。

Because of its good biocompatibility and moderate degradation rate, Zinc alloys are expected to be the ideal candidate materials for the new generation biodegradable vascular stents. But the clinical application of Zinc alloy stents is facing the challenges of self-aging and insufficient work-hardening ability. The present project proposal proposes the new biodegradable Zn-Cu-based alloys will be designed with the aid of first-principle calculations on the basis of the recently developed anti-aging Zn-Cu binary alloy. The thermal stability and dynamic recrystallization temperature of Zn-Cu-based alloy will be improved by introducing some proper solid solution atoms and tiny dispersed second phase particles by low-alloying or micro-alloying means. The bimodal microstructure which is benefit to produce good strength and plasticity combination will be constructed in new Zn-Cu-based alloy by regulating the extrusion and heat treatment process. Through these means, the non-basal plane dislocations in zinc alloy matrix will be activated effectively, and the interaction between the different dislocations, the dislocation and grain boundary/twin boundary, solid solution atoms and the tiny second phases will be promoted and improved. Consequently, the self-aging resistance and work hardening ability of Zn-Cu-X system alloy will be realized. The in vitro corrosion and corrosion fatigue behavior of zinc alloy will be studied and the relationship between the microstructure and corrosion & corrosion fatigue behavior will be revealed. By means of macro and micro analysis and calculation simulation, the mechanisms of self-aging resistance and work-hardening ability of the new Zn-Cu-X base alloy will be analyzed systematically, and the relationships between the alloy design, deformation process, microstructure and mechanical & degradation behavior will be established. The research achievements from the present project will lay the materials design theory and technology basis for the research & development and clinical applications of biodegradable zinc alloys with high performance for vascular stents.