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.

非技术摘要解决极端条件下金属耐久性的局限性仍然是该行业面临的一项关键挑战。当前的解决方案通常依赖于昂贵且稀缺的元素，这凸显了对更可持续的替代品的需求。浓缩合金 (CCA)，利用局部化学有序 (LCO) 来增强损伤容限，而不依赖于这些关键元素，特别是在低温下，LCO 是指金属内原子对或簇的重复配置。它可以有目的地影响变形机制，而不会产生清晰的界面，而清晰的界面是裂纹的常见部位，该提案旨在通过策略性地利用不同类型的 LCO，设计出具有独特变形机制的 CCA，同时增强强度、延展性和韧性。该研究将采用综合实验和计算方法来开发 LCO 增强的 CCA，以避免传统合金在低温下出现的典型脆化现象。该提案将利用原位电子显微镜和先进技术研究变形机制。这项工作的更广泛影响将扩展到可持续金属技术的发展、未来材料科学家的教育和推广。激发高中生和教师的努力，特别是来自代表性不足的社区的学生和教师的努力，培养可持续合金设计领域的下一代创新者。技术摘要本研究计划旨在开发新型面心立方 (fcc) 复杂浓缩合金（CCA）以提高工程材料在恶劣环境条件下的性能，特别是在低温下，该方法的核心是利用局部化学有序（LCO）来诱导合金内表现出负内在堆垛层错能的断层塑性机制。 SFE）。堆垛层错（马氏体的最小成分）提供了理论上最佳的细化结构，具有最小的应变局部化，因此，断层塑性可以改善强度、延展性和韧性，特别是在低温下。通过考虑 LCO 的影响，实现断层塑性的固有挑战，其中所需的低或负 SFE 同时促进马氏体转变，该方法将先进的生产和表征技术与热力学和密度泛函理论计算相结合，旨在使用 LCO 设计 CCA。该效应旨在抑制从 fcc 到 hcp、bcc 或 bct 马氏体的转变，并了解断层塑性如何机械地影响材料性能。该提案的智力价值在于其探索和利用的潜力。 fcc CCA 中的亚稳定性和 LCO，可增强低温环境中的稳健性。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。