高性能细晶甚至超细晶变形镁合金板材的生体腐蚀降解行为与微观组织相关性研究

Magnesium alloy is a novel type of degradable biomaterials, which has a wide application prospect in hard tissue implants and intravascular implants. However, accerlated corrosion occurs after conventional magnesium alloys are implanted into human bodies. Therefore, it is of great significance to improve corrosion resistance and reduce the degradation rate of magnesium implants to satisfy the requirement for its degradation limit. The applicants propose the thought that the novel biomedical fine-grained or ultrafine-grained magnesium alloy sheets are prepared by high strain rate rolling with the combination of micro-alloying, rolling process control and heat treatment for microstructure modification to study the relevance between their biocorrosion degradation behaviors and microstructural features. The microstructure features including grain size, nano-size precipitation, texture, grain boundary and etc will be systematically investigated, and their mechanical properties including tensile strength, plasticity, bending strength, compressive strength, fatigue resistance and etc will be clarified. The in-vitro corrosion regularities and the degradation regularities of mechanical properties in the simulated body environments will be explored. The relevance between the biocorrosion degradation behaviors and microstructure features will be developed. The in-vitro biocorrosion behaviors and the mechanical failure mechanisms will be revealed. The effects of high strain rate rolling on corrosion improvement and the corresponding action mechanisms will be clarified. The solutions to achieve the effective control of the biodegradation rate will be found. The in-vivo biocorrosion behaviors will be further studied. The biomechanical safety and biocompatibility will be roundly evaluated. The project will provide the scientific grounds and accumulate the experimental data for the preparation of novel biomedial degradable magnesium alloys.

镁合金是新型可降解医用材料，在用作硬组织和血管内植入物方面前景广阔。然而，常规镁合金植入人体后存在加速腐蚀。如何提高其耐蚀性、降低植入物的降解速率进而达到植入器件降解周期的要求尤为重要。本申请提出采用高应变速率轧制制备高性能细晶甚至超细晶镁合金板材，通过微合金化、轧制工艺和热处理相结合调控微观组织，研究其生体腐蚀降解行为与微观组织特征的相关性。系统研究板材的微观组织特征（如晶粒尺寸、纳米析出相特征、织构和晶界特性等），明确力学性能特点（如拉伸强度、塑性、弯曲强度、压缩强度和抗疲劳性能等）；研究其在模拟生理环境中的腐蚀规律和力学性能退化规律，建立降解行为与微观组织特征的相关性，揭示体外腐蚀机理和力学失效机理，阐明高应变速率轧制提高耐蚀性的作用机制，探寻有效调控镁合金降解速率的途径；深入研究体内降解特性，全面评价生物力学安全性和生物相容性，为制备新型可降解医用镁合金材料提供科学基础和实验依据。

镁合金是新型可降解医用材料，在用作硬组织和血管内植入物方面前景广阔。然而，常规镁合金植入人体后存在加速腐蚀。如何提高其耐蚀性、降低植入物的降解速率进而达到植入器件降解周期的要求尤为重要。本项目选取Mg-(4~5)Zn合金和ZK60合金为研究对象，选择的微合金化元素包括Sr、Ca和Mn等，通过微合金化、高应变速率轧制和热处理相结合调控合金的微观组织，研究合金的生体腐蚀降解行为与显微组织特征的相关性。通过系统的实验工作和深入的理论分析，取得了一系列重要实验结果和结论：阐明了Sr、Ca和Mn合金化对Mg-Zn系合金（铸态、固溶态和轧制态）微观组织、力学性能和降解行为的影响规律，揭示了相关的作用机制；探明了细晶甚至超细晶粒Mg-4Zn合金板材的降解行为与力学性能退化规律；明确了高应变速率轧制对Mg-Zn系合金降解行为的影响及其作用机制，提出了调控镁合金降解速率的途径；建立了Mg-Zn系合金力学性能和降解行为与析出相特征的相关性，发展了基于GP区和纳米析出相调控同时提高合金强度和耐蚀性的新方法；阐明了Mg-Zn系合金的应力腐蚀行为特点，揭示了微合金化元素的作用机制；全面评价了Mg-Zn-Sr合金的生物相容性，为新型可降解医用镁合金材料的研制提供了科学基础和积累了大量实验依据。