Design and In-vitro Characterization of Ni-free Biocompatible Shape Memory Alloys

0731133 Karaman该项目将开发钛铌二元和三元合金作为镍钛形状记忆合金的替代品，因为它具有更好的可加工性、更好的生物相容性、更好的耐腐蚀性和接近人体骨骼弹性模量的较低模量。这项工作解决了这些合金目前存在的两个问题：低相变应变和疲劳响应。该项目将改善这些材料的性能，首先从理解单晶研究中的微观结构机制开始，然后进入多晶，通过考虑三元合金添加剂和使用单晶中开发的知识库，通过孪生和相变诱导纳米晶化进行晶粒细化，以增强循环响应，结合新的加工技术进行纹理化，并对微观结构和纹理演变进行建模，最后进行全尺寸表征。这些种类的材料普遍用于各种生物医学应用，例如血管内支架、医疗和牙科线和填充物以及若干外科手术器械。由于镍的毒性，人们迫切需要设计出无镍形状记忆合金，这种合金具有完全的生物惰性成分，对杂质和夹杂物的敏感性较低，耐腐蚀性更好，疲劳响应更稳定，疲劳寿命可预测。该项目的更广泛影响是潜在的一类新的生物相容性材料，具有更好的耐腐蚀性和更低的毒性。该研究还将通过NSF REU计划为本科生提供参与机会。

0731133KaramanThe project will develop Titanium-Niobium binary and ternary alloys as an alternative to Nickel-Titanium shape memory alloys since it has better processibility, better biocompatibility, better corrosion resistance and lower modulus near the elastic modulus of human bone. This work addresses two current problems with these alloys: low transformation strains and fatigue response. The project will improve these material properties, starting first with the understanding the microstructural mechanisms in single crystal studies and then move into polycrystals, by considering ternary alloy additions and using the knowledge base developed in the single crystals, grain refinement via twinning- and transformation-induced nanocrystallization for enhanced cyclic response, texturing using combination of novel processing techniques and modeling the microstructure and texture evolution, and eventually full scale characterization. These kinds of materials are popularly used for various biomedical applications such as endovascular stents, medical and dental wires and fillers and several surgical instruments. Due to the toxicity of Nickel, there is an urgent need for the design of Nickel-free shape memory alloys with completely bio-inert constituents, less-sensitivity to impurities and inclusions, better corrosion resistance, more stable fatigue response, and predictable fatigue life.The broader impacts of this project are in the potential of a new class of biocompatible materials with improved corrosion resistance and less potential for toxicity. The research will also offer opportunities for undergraduate participation through the NSF REU program.