低弹性模量生物医用型高熵合金的成分设计及性能研究

Stress shielding effect of metallic biomaterials due to the high elastic modulus would induce bone resorption during long term service. High entropy alloys (HEAs) exhibit excellent mechanical, physical and chemical properties owing to the characteristics of multi-principal element composition and simple solid solution structure. Good corrosion resistance and biocompatibility of TiZr-transition element HEAs are benefit for biomedical application. To further decreasing the elastic modulus of these HEAs is the key issue for promoting the HEAs as implant materials in field of biomedical application. Moreover, limited work has been done for understanding the correlation of elastic modulus, biocorrosion behaviors and biocompatibility with composition and microstructure of HEAs. In this project, biomedical HEAs with low elastic modulus, high strength, excellent biocorrosion resistance and good biocompatibility will be designed and developed via proper composition design and element addition based on Ti-Nb-Ta-Zr-Hf HEA system. The influence of the alloy composition on the phase structural stability will also be clarified. The correlation of mechanical properties, biocorrosion behavior and biocompatibility with alloy composition and microstructure, and the corresponding mechanism will also be illuminated. The proposed project, which will contribute to the enrichment of fundamentals of biomedical HEAs, extension of the applications of HEAs, is of great scientific significances.

医用金属植入材料在长期服役期间面临弹性模量过高引起应力遮挡效应导致骨吸收的问题。高熵合金多主元和简单固溶体结构的特点，表现出优异的力学、物理和化学性能。TiZr-过渡族金属高熵合金体系具有良好的耐腐蚀性能和生物相容性，使其具有在生物医用材料领域的应用潜力，进一步降低其弹性模量是推进高熵合金作为植入材料在生物医用领域应用所面临的关键问题。同时，关于高熵合金的弹性模量、生物腐蚀行为和生物相容性与合金成分、微观结构的关联也缺乏系统深入研究。本项目从Ti-Nb-Ta-Zr-Hf系高熵合金出发，通过适当的成分设计或元素添加设计开发具有低弹性模量、高强度、优异耐腐蚀性能和良好生物相容性的生物医用型高熵合金，并揭示合金成分对结构稳定性的影响，阐明合金力学性能、生物腐蚀行为和生物相容性与合金成分和微观结构间的关联及机制。本项目研究将丰富生物医用型高熵合金的基础理论、拓展高熵合金的应用，具有重要的科学意义。

医用金属植入材料在长期服役期间面临弹性模量过高引起应力遮挡效应导致骨吸收的问题。高熵合金多主元和简单固溶体结构的特点，表现出优异的力学、物理和化学性能。TiZr-过渡族金属高熵合金体系具有良好的耐腐蚀性能和生物相容性，使其具有在生物医用材料领域的应用潜力，进一步降低其弹性模量是推进高熵合金作为植入材料在生物医用领域应用所面临的关键问题。基于[Ti, Zr, Hf]14(Nb, Ta)m固溶体结构模型，本项目设计开发出了生物医用新型TiZrHfNbTa系高熵合金，并系统研究了该系高熵合金成分与微观结构、力学性能和生物相容性的关联。.结果表明，冷轧退火后的Ti-Zr-Hf-Nb-Ta系高熵合金为单相BCC结构，其中Ti27.78Zr27.78Hf27.78Nb8.33Ta8.33（at.%）高熵合金的塑性变形量和杨氏模量分别约为9.2%和73GPa，杨氏模量明显低于商业医用金属材料，可有效地减弱 “应力遮挡效应”。TiZrHfNbTa高熵合金具有优于Ti6Al4V合金的耐磨损性能。该系高熵合金在Hank’s溶液中具有良好的耐腐蚀性能，能够自发钝化，无点蚀现象，具有较低的腐蚀电流密度和钝化电流密度（10-6-10-5Acm-2）。这归因于该合金在 Hank’s 溶液中能够形成成分为 TiO2、ZrO2、HfO2、Nb2O5和Ta2O3 高保护性表面钝化膜。TiZrHfNbTa高熵合金具有良好的生物相容性。与纯Ti和纯Hf相比，表现出更好的润湿性和更高的表面自由能，更有利于蛋白质的吸附和细胞黏附。NIH3T3小鼠成纤维细胞在该合金表面具有高的存活率，能够较好地进行生长、代谢和增殖。.综上所述，TiZrHfNbTa高熵合金具有低杨氏模量、较高的强度、良好的耐腐蚀性能、耐腐蚀磨损和的生物相容性。本项目研究成果对丰富生物医用型高熵合金的基础理论和生物医用金属材料选材，具有重要的工程和科学意义。