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：强度越来越高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轻量化以实现更节能的运输，有几种途径可以通过控制缺陷来增强强度。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，这种失败并不是因为缺乏材料工程，也不是因为材料设计或创新。立即处理解决相反，从材料变形物理学的角度来看，现有方法的范围过于有限，本研究通过考虑控制材料结构的新颖设计途径以及控制强度的缺陷来解决这一问题。该项目适用于化学复杂性增加的先进材料，这是现代工程应用所需要的，一个超越传统机构障碍的交互式在线学习模块——工程教育中的力学互动团队（MINT）倡议——正在开发中，以吸引学生的合作。在合作大学与新虚拟学习模块专注于材料科学的前沿主题，最初的重点是通过石溪大学的科学与工程女性项目扩大到本科生，并通过与合作伙伴的合作进一步扩大到使用相关设计问题的职业人士。加州大学欧文分校先进铸造研究中心。技术描述：这项研究通过对位错成核和传播作为纳米结构中限速变形机制的基本理解，使材料具有接近理想的强度。缺陷限制以及与晶界和晶格溶质的相互作用成为塑性局部障碍的合金需要回答的具体研究问题包括：（i）对于溶质修饰界面处的位错成核和位错成核来说，重要的过渡态和相关的能量障碍是什么。纳米级合金晶体内的传播，(ii) 掺杂时的界面结构和能量变化如何改变位错成核/传播，以及 (iii) 晶粒内的溶质原子如何，它可能充当局部钉扎点，但也会改变晶格的特性，影响位错传播？ 这项研究的一个实际假设是，可以通过协同掺杂来最大化纳米晶合金的强度，以稳定晶界以防止局部塑性和延迟。这一假设结合了原子建模、多模态结构表征和独特的微观机械测试，可以抑制缺陷成核，同时抑制位错通过纳米晶内部的传播。正在纳米结构铝和铜合金中进行测试，它们本质上不同的堆垛层错能量将提供不同的受限滑移事件，从广义上讲，这项研究将定义纳米工程金属材料的新强化范例，并建立溶质的机械基础。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。