NSF-BSF: Stress-Assisted Structural Phase Transformations and Plasticity in Bicontinuous Nanomaterials

NSF-BSF：双连续纳米材料中的应力辅助结构相变和塑性

• 批准号: 2208681
• 负责人: Niaz Abdolrahim
• 金额: $ 28.74万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2208681&HistoricalAwards=false
• 关键词: NSF; BSF; Stress; Assisted; Structural

Nanoporous (NP) metals with tortuous surfaces and large surface-to-volume ratio are promising candidates for various important advanced technologies, from electrochemical sensors/actuators and fuel cell filters to energy conversion and storage systems. However, a hindrance to widespread technological application of NP metals is that they fail suddenly and with minimal uniform macroscopic plastic deformation. This award supports fundamental research to explore new ways of enabling homogeneous deformation in bicontinuous NP materials via alternative phase transformation (PT) mechanisms. The homogenous PT mechanisms would prevent localized deformation and, thus, enhance ductility across the whole system. The insights to be gained in this project will enable design of strong and ductile NP materials by utilizing metastable phases which cannot be obtained in conventional bulk metals and alloys. The fundamental mechanisms elucidated in this project will be applicable to other refractory materials and can also be scaled up for large-scale structural and functional applications. The award will also support undergraduate summer internships, a workshop on exploring nanotechnology for high school students with focus on underrepresented minority participation, and international student exchange.This project seeks to enable mechanisms of uniform (instead of local) PT and achieve significantly improved plastic deformability in Molybdenum (Mo)-based NP metals. Extreme stresses (on the order of tens of gigapascals) are required to thermodynamically drive a PT in Mo from a low-energy body centered cubic phase to a high-energy face centered cubic state instead of activating dislocation nucleation or propagation mechanisms. While this PT has been observed locally and at the atomic scale, it remains totally unclear whether it can occur homogenously to significantly modify mechanical behavior of specimens larger than about hundred nanometers in size. This project will study the combination of microstructure features including 1) small (defect-free) ligaments, 2) tortuosity of the structure, and 3) interfaces between Mo and a secondary material, that will enable a uniform distribution of high internal stresses through the entirety of NP composite structures and promote uniform deformation and better ductility. Molecular dynamics simulations and nanomechanical testing experiments with finite elements analysis will be integrated to study the mechanical response and post mortem microstructures for potential PT-based uniform plastic deformation.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.

具有曲折表面和大表面积与体积比的纳米多孔（NP）金属是各种重要先进技术的有希望的候选者，从电化学传感器/执行器和燃料电池过滤器到能量转换和存储系统。然而，NP金属广泛技术应用的一个障碍是它们突然失效并且具有最小的均匀宏观塑性变形。该奖项支持基础研究，探索通过替代相变（PT）机制实现双连续纳米颗粒材料均匀变形的新方法。同质 PT 机制将防止局部变形，从而增强整个系统的延展性。该项目获得的见解将能够利用传统块体金属和合金中无法获得的亚稳态相来设计坚固且具有延展性的纳米粒子材料。该项目阐明的基本机制将适用于其他耐火材料，也可以扩大规模用于大规模结构和功能应用。该奖项还将支持本科生暑期实习、为高中生探索纳米技术（重点关注少数族裔参与）和国际学生交流的研讨会。该项目旨在实现统一（而不是局部）PT 机制，并显着改善塑性变形能力钼 (Mo) 基 NP 金属。需要极端应力（大约数十吉帕斯卡）来热力学驱动Mo中的PT从低能体心立方相转变为高能面心立方态，而不是激活位错成核或传播机制。虽然这种 PT 已经在局部和原子尺度上被观察到，但仍然完全不清楚它是否可以均匀发生以显着改变尺寸大于约一百纳米的样本的机械行为。该项目将研究微观结构特征的组合，包括 1) 小（无缺陷）韧带，2) 结构的曲折，以及 3) Mo 和辅助材料之间的界面，这将使高内应力通过NP复合材料结构的整体，促进均匀变形和更好的延展性。将分子动力学模拟和纳米力学测试实验与有限元分析相结合，研究潜在的基于 PT 的均匀塑性变形的机械响应和死后微观结构。该奖项反映了 NSF 的法定使命，并通过使用基金会的评估进行评估，认为值得支持。智力价值和更广泛的影响审查标准。