Collaborative Research: Manufacturing of Low-cost Titanium Alloys by Tuning Highly-indexed Deformation Twinning

该基金支持钛合金制造的基础研究，促进科学和工程的进步。钛合金具有轻质、高强度、高韧性、耐高温、耐腐蚀和生物相容性等优点，是一种很有前途的结构材料，在交通运输（如飞机发动机部件）和医疗保健（如人体植入物）方面有许多关键应用。然而，钛合金的制造需要添加昂贵的合金元素和较高的加工温度，这导致其成本高，极大地限制了其商业用途。该项目研究了变形孪晶的科学机制，并开发了一种低成本制造先进轻质钛合金的原型系统。结合实验、计算和机器学习的努力，寻找具有低成本合金元素的钛合金的新成分，并激活新的变形机制，以实现其室温制造。该项目产生的新知识推动了钛工业的发展，促进了减少二氧化碳排放和改善人类健康的技术，从而促进了国家的繁荣和福祉。这项研究提供了一个平台，培训下一代钛专家和熟练的劳动力，特别是那些来自代表性不足的群体，在先进材料和高性能计算的制造方面。该项目由先进制造（AM）计划和促进竞争研究的既定计划（EPSCoR）共同资助。该项目旨在通过一种新的合金设计和加工策略，推进具有成本效益的钛合金室温制造。在这种策略中，大部分（大于50%体积）的体心立方β相在浇铸和均质处理后使用低成本元件在室温下稳定。此外，通过利用孪生诱导塑性（TWIP）和相变诱导塑性（TRIP）耦合机制激活β相中足够的高指数化变形孪晶模式，这些合金在随后的冷变形过程中的室温延展性和可加工性得到改善。遵循两种具体的方法，包括实验，模拟和机器学习的集成。第一种方法是通过先进的表征、晶体学模型和原子模拟来识别和调整具有代表性的钛合金相变和高指数孪晶之间的耦合机制。第二种方法是通过机器学习模型之间的迭代反馈，根据第一性原理计算，以及高通量制造和机械测试实验，操纵和研究合金对这些合金的孪生和室温可加工性的影响。这些结果指导了含有低成本合金元素的β相稳定钛合金的发现，并获得了较高的室温可加工性。最后，对具有优化成分的大型钛合金样品进行轧制和拉伸成特定形状的冷变形处理，并对其力学行为进行测试，以验证其室温可加工性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This grant supports fundamental research in titanium alloys manufacturing and promotes the progress of science and engineering. Titanium alloys are promising structural materials due to their lightweight, high strength and toughness, high temperature and corrosion resistance, and biocompatibility and have many critical applications in transportation, such as airplane engine components, and healthcare, such as human implants. However, the manufacturing of titanium alloys requires the addition of expensive alloying elements and high processing temperatures, which leads to their high costs and significantly restricted commercial use. This project investigates the scientific mechanisms involved in deformation twinning and develops a prototype system for low-cost manufacturing of advanced lightweight titanium alloys. A combination of experimental, computation, and machine learning efforts is performed to search for new compositions of titanium alloys with low-cost alloying elements and activate novel deformation mechanisms in order to achieve their room-temperature manufacturing. The new knowledge generated by this project advances the titanium industry and promotes technologies to reduce carbon dioxide emissions and improve human health, thus promoting national prosperity and welfare. This research provides a platform to train the next generation of titanium experts and skilled workforce, especially those from underrepresented groups, in the manufacturing of advanced materials as well as high-performance computing. This project is jointly funded by Advanced Manufacturing (AM) program and the Established Program to Stimulate Competitive Research (EPSCoR).This project aims to advance cost-effective room-temperature manufacturing of titanium alloys by a novel alloy design and processing strategy. In this strategy, a large portion (greater than 50 volume percent) of the body-centered cubic beta phase is stabilized at room temperature using low-cost elements after casting and homogenization processes. Furthermore, room-temperature ductility and workability of these alloys in the subsequent cold deformation process are improved by activating sufficient highly-indexed deformation twinning modes in the beta phase utilizing coupled twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) mechanisms. Two specific approaches, involving integration of experiment, simulation and machine learning, are followed. The first approach is to identify and tune the coupling mechanisms between phase transformations and highly-indexed twinning in representative titanium alloys through advanced characterization, crystallography models and atomistic simulations. The second approach is to manipulate and investigate alloying effects on twinning and room-temperature workability of these alloys by iterative feedback between the machine learning models, informed by first-principles calculations, and high-throughput fabrication and mechanical testing experiments. These results guide the discovery of beta phase stabilized titanium alloys containing low-cost alloying elements and attain high room-temperature workability. Finally, large-scale samples of titanium alloys with optimized compositions are cold deformation processed by rolling and drawing into specific shapes and tested for mechanical behavior to verify their room-temperature workability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.