Collaborative Research: Deformation Mechanisms in Microstructurally Tailored High Strength Alloys Near the Ideal Limit

合作研究：接近理想极限的微观结构定制高强度合金的变形机制

• 批准号: 2310307
• 负责人: Timothy Rupert
• 金额: $ 42万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2310307&HistoricalAwards=false
• 关键词: Collaborative; Research; Deformation; Mechanisms; Microstructurally

NON-TECHNICAL DESCRIPTION: Materials with higher and higher strengths are often the target of materials scientists for structural engineering applications – stronger materials enable safer structures as well as lightweighting for more energy-efficient transportation. Several pathways are available for enhancing strength through control over defects in the material. However, efforts to-date have failed to bring material strengths anywhere near the holy grail of strengthening, referred to as the ideal strength. This failure has not come from a lack of materials engineering, nor would innovations in materials design or processing immediately solve the problem. Instead, prior approaches have been too limited in scope from the viewpoint of the material’s deformation physics, which is addressed in this research by considering novel design pathways for controlling material structure and, in turn, the defects that govern strength. The findings of this project are applicable to advanced materials with increased chemical complexity, which are desired for modern engineering applications. An interactive online learning module transcending traditional institutional barriers – denoted the Mechanics Interactive Teaming (MINT) initiative in engineering education – is being developed to engage students cooperatively at the partnering universities with new virtual learning modules focused on cutting-edge topics in materials science. The initial focus on graduate curricula is being broadened to reach undergraduates through the Women in Science and Engineering Program at Stony Brook University and further expanded for working professionals using relevant design problems through collaboration with the Advanced Casting Research Center at UC Irvine.TECHNICAL DESCRIPTION: This research enables materials with near-ideal strength by developing a fundamental understanding of dislocation nucleation and propagation as rate-limiting deformation mechanisms in nanostructured alloys where defect confinement and interaction with grain boundary and lattice solutes act as local barriers to plasticity. Specific research questions to be answered include: (i) what are the important transition states and associated energy barriers for dislocation nucleation at solute-decorated interfaces and for propagation within a nanoscale alloy crystal, (ii) how does interfacial structure and energy variation upon doping alter dislocation nucleation/propagation, and (iii) how do solute atoms inside the grain, which can potentially act as local pinning points but also alter the properties of the lattice, influence dislocation propagation? A practical hypothesis of this research is that the strength of nanocrystalline alloys can be maximized by synergistic doping to stabilize the grain boundaries against local plasticity and delay defect nucleation while simultaneously inhibiting dislocation propagation through the nanograin interiors. Using a combination of atomistic modeling, multi-modal structural characterization, and unique micromechanical testing, this hypothesis is being tested in nanostructured aluminum and copper alloys, where their intrinsically different stacking fault energies will provide access to different confined slip events. In a broad sense, this research will define new strengthening paradigms in nanoengineered metallic materials and establish the mechanistic underpinnings of solute-biased interfacial energy landscapes for understanding fundamental dislocation physics in confined slip 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.

非技术描述：具有越来越高强度的材料通常是材料科学家在结构工程应用中的目标-更强的材料可以实现更安全的结构以及更节能的运输的轻量化。有几种途径可以通过控制材料中的缺陷来提高强度。然而，迄今为止的努力未能使材料强度接近强化的圣杯，即理想强度。这种失败不是由于缺乏材料工程，也不是材料设计或加工的创新能立即解决问题。相反，从材料变形物理的角度来看，先前的方法在范围上过于有限，本研究通过考虑控制材料结构的新设计途径以及反过来控制强度的缺陷来解决这一问题。该项目的研究结果适用于具有更高化学复杂性的先进材料，这是现代工程应用所需要的。一个超越传统制度障碍的互动式在线学习模块——被称为工程教育中的力学互动团队（MINT）计划——正在开发中，以吸引合作大学的学生合作，使用新的虚拟学习模块，重点关注材料科学的前沿主题。最初的重点是研究生课程，通过石溪大学的女性科学与工程项目扩大到本科生，并通过与加州大学欧文分校先进铸造研究中心的合作，进一步扩大到使用相关设计问题的专业人士。技术描述：本研究通过对纳米结构合金中作为限速变形机制的位错形核和扩展的基本理解，使材料具有接近理想的强度。在纳米结构合金中，缺陷限制和与晶界和晶格溶质的相互作用是塑性的局部障碍。需要回答的具体研究问题包括：(i)在溶质修饰界面上位错成核和纳米级合金晶体内扩展的重要过渡态和相关能垒是什么；（ii）掺杂后界面结构和能量变化如何改变位错成核/扩展；（iii）晶粒内的溶质原子如何影响位错扩展，它们可能充当局部钉住点，但也会改变晶格的性质。本研究的一个实际假设是，协同掺杂可以最大限度地提高纳米晶合金的强度，从而稳定晶界，防止局部塑性，延缓缺陷成核，同时抑制位错在纳米晶粒内部的传播。结合原子建模、多模态结构表征和独特的微观力学测试，这一假设正在纳米结构铝和铜合金中得到验证，在纳米结构铝和铜合金中，它们本质上不同的层错能将提供不同的受限滑动事件。从广义上讲，本研究将定义纳米工程金属材料的新强化范式，并为理解局限滑移环境下的基本位错物理建立溶质偏向界面能景观的机制基础。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。