CAREER: Local Chemical Ordering-Assisted Faulting Plasticity in Complex Concentrated Alloys

职业：复杂浓缩合金中的局部化学有序辅助断层塑性

• 批准号: 2339155
• 负责人: Hyunseok Oh
• 金额: $ 57.96万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-03-01 至 2029-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2339155&HistoricalAwards=false
• 关键词: CAREER; Local; Chemical; Ordering; Assisted

NON-TECHNICAL SUMMARYAddressing the limitations of metal durability in extreme conditions remains a critical challenge for the industry. Current solutions often depend on expensive and scarce elements, underscoring the need for more sustainable alternatives. This research proposes the development of a novel class of complex-concentrated alloys (CCAs) that utilize local chemical ordering (LCO) to enhance damage tolerance without the reliance on these critical elements, particularly at cryogenic temperatures. LCO refers to the repetitive configurations of atomic pairs or clusters within metal solid solutions. It can purposefully influence deformation mechanisms without creating clear interfaces, which are common sites for cracks. By strategically harnessing different types of LCO, this proposal aims to design CCAs that exhibit a unique deformation mechanism, enhancing strength, ductility, and toughness while avoiding the typical embrittlement seen in conventional alloys at low temperatures. The research will employ integrated experimental and computational methods to develop CCAs reinforced with LCO. This proposal will investigate the deformation mechanism using in situ electron microscopy and advanced characterization methods, with a focus on behavior at cryogenic temperatures, which could pioneer novel mechanisms for toughening materials across various applications. The broader impacts of this work will extend to the development of sustainable metal technologies, the education of future materials scientists, and the outreach efforts to inspire high school students and teachers, particularly from underrepresented communities, fostering the next generation of innovators in the field of sustainable alloy design.TECHNICAL SUMMARYThis research proposal aims to develop novel classes of face-centered cubic (fcc) complex concentrated alloys (CCAs) to enhance the performance of engineering materials under severe environmental conditions, especially at cryogenic temperatures. Central to this approach is the utilization of local chemical ordering (LCO) to induce a faulting plasticity mechanism within alloys that exhibit negative intrinsic stacking fault energy (SFE). Stacking faults—the smallest components of martensite—provide a theoretically optimal refined structure with minimal strain localization. Therefore, faulting plasticity could offer improvements in strength, ductility, and toughness, particularly at cryogenic temperatures. This proposal addresses the inherent challenges of achieving faulting plasticity, where the low or negative SFE required concurrently promotes martensitic transformation, by considering the effects of LCO. The methodology combines advanced production and characterization techniques with thermodynamic and density-functional theory calculations aimed at designing CCAs with an LCO effect tailored to suppress the transformation from fcc to hcp, bcc, or bct martensite, and to understand how faulting plasticity mechanically influences material properties. The intellectual merit of this proposal lies in its potential to explore and harness metastability and LCO within fcc CCAs for enhanced robustness in cryogenic environments.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.

在极端条件下，金属耐用性的局限性的非技术总结对于该行业来说仍然是一个至关重要的挑战。当前的解决方案通常取决于昂贵和稀缺的要素，强调了对更可持续的替代方案的需求。这项研究提出，利用局部化学有序（LCO）的新型复合浓缩合金（CCA）的发展发展，以提高损伤耐受性，而不会依赖这些关键元素，尤其是在低温温度下。 LCO是指金属固体溶液中原子对或簇的重复构型。它可以故意影响变形机制，而无需创建清晰的接口，这是裂纹的常见位置。通过战略性利用不同类型的LCO，该提案旨在设计CCA，以揭示独特的变形机制，增强强度，延性和韧性，同时避免在低温下传统合金中看到的典型互惠率。该研究将采用集成的实验和计算方法来开发由LCO加强的CCA。该建议将使用原位电子显微镜和高级表征方法研究变形机制，重点是在低温温度下的行为，这可能会先开拓各种应用跨各种应用材料的新型机制。这项工作的更广泛的影响将扩展到可持续金属技术的发展，对未来材料科学家的教育以及激发高中生和老师的宣传工作，尤其是来自代表性不足的社区，促进了可持续合金设计领域的下一代创新者。在严重的环境条件下，尤其是在低温温度下的工程材料的性能。这种方法的核心是利用局部化学有序（LCO）来诱导合金内的断层可塑性机制，该机制暴露了负阴性固有堆叠断层能（SFE）。堆叠断层（马氏体的最小成分）提供了理论上最佳精制结构，并具有最小的应变定位。因此，断层可塑性可以改善强度，延展性和韧性，尤其是在低温温度下。该提案解决了实现断层可塑性的继承挑战，在考虑LCO的影响下，低或负SFE同时促进了马氏体转变。该方法将先进的生产和表征技术与热力学和密度功能理论计算相结合，旨在设计CCA，旨在量身定制的LCO效应，以抑制从FCC到HCP，BCC或BCT Martensite的转化，并了解故障多样性如何机械影响材料。该提案的智力优点在于它有潜力探索和利用FCC CCA中的LCO和LCO在低温环境中增强鲁棒性。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛影响的审查标准来评估通过评估而被认为是珍贵的。