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

这项资助支持钛合金制造的基础研究，促进了科学和工程的进步。钛合金具有轻质、高强度、高韧性、耐高温、耐腐蚀、生物相容性好等优点，在航空发动机零部件、人体植入等医疗保健领域有着重要的应用前景。然而，钛合金的制造需要添加昂贵的合金化元素和较高的加工温度，这导致其成本较高，大大限制了其商业应用。该项目研究了变形孪生的科学机制，并开发了一个低成本制造先进轻质钛合金的原型系统。通过实验、计算和机器学习相结合的方法，寻找具有低成本合金化元素的钛合金的新成分，并激活新的变形机制，以实现钛合金的室温制造。该项目产生的新知识推动了钛行业的发展，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利。这项研究提供了一个平台，以培训下一代钛专家和熟练劳动力，特别是那些来自代表不足的群体的人，在先进材料制造和高性能计算方面。该项目由先进制造(AM)计划和已建立的激励竞争研究计划(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来促进钛合金的低成本室温制造。在这一策略中，大部分以身体为中心的立方贝塔相(大于50%的体积百分比)在铸造和均化过程后使用低成本元素在室温下稳定下来。此外，通过利用耦合孪生诱导塑性(TWIP)和相变诱导塑性(TRIP)机制在β相中激活足够的高指数变形孪生模式，改善了这些合金在随后的冷变形过程中的室温塑性和加工性能。采用了实验、仿真和机器学习相结合的两种具体方法。第一种方法是通过先进的表征、结晶学模型和原子模拟来识别和调整典型钛合金中的相变和高折射率孪晶之间的耦合机制。第二种方法是通过机器学习模型与高通量制造和力学测试实验之间的迭代反馈，操纵和研究合金化对这些合金的孪生和室温加工性能的影响。这些结果指导发现了含有低成本合金化元素的β相稳定钛合金，并获得了较高的室温加工性。最后，具有优化成分的大型钛合金样品通过轧制和拉伸成特定形状进行冷变形处理，并进行机械行为测试，以验证其室温可加工性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.