Excess Vacancy Enabled Transformations in Light Metal Alloys

过剩的空位促进了轻金属合金的转变

• 批准号: 2320355
• 负责人: Michael Falk
• 金额: $ 69.01万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2320355&HistoricalAwards=false
• 关键词: Excess; Vacancy; Enabled; Transformations; Light

NON-TECHNICAL SUMMARYInnovating processes for lightweight metal alloy manufacture advances public welfare and secures the national defense by enabling efficient production of new materials that provide strength without adding weight in applications from vehicles and protective equipment to space exploration. This award supports basic scientific studies regarding how atomic structures respond to extreme conditions of temperature and strain that result in defects called vacancies, where atoms are missing from the metal’s crystal structure. This research advances the understanding of why and how vacancies cluster with solute atoms that differ from the primary metal, gathering into small bubbles called voids and encouraging the formation of strengthening particles.Multiple experimental techniques are used: positively charged particles are used to measure defects; atom probe reveals locations of different elements in the crystal structure; and electron microscopy images show larger scale features such as voids. Simulations predict how vacancies, solute and voids interact to better interpret the experimental data. These simulations also provide estimates of how the rate at which voids form, varies with temperatures, vacancy densities, and solute chemistries and densities. Experimental data are used to guide the choices of simulations and to check the validity of the simulations. In the process, this work advances simulation capabilities.This project engages undergraduates from Morgan State University, a nearby historically Black university, to foster the success of a newly emerging program that provides access to engineering degrees not currently offered at that university. The investigators also are planning to host an “Extreme Vacancy Engineering” workshop.TECHNICAL SUMMARYThe proposed research program aims to accelerate the development of new light alloys and processing routes by expanding our fundamental understanding of how vacancy supersaturation alters the thermodynamics of vacancy clustering, vacancy-solute complex formation, and void nucleation in ways that promote solute clustering and intermetallic precipitation. Alloys over a range of compositions are subjected to quenching and deformation to enhance vacancy densities in a controlled manner. Analysis is performed using an emerging computational methodology, transition interface sampling, coupled with targeted characterization using positron annihilation spectroscopy, atom probe tomography, and transmission electron microscopy in concert with molecular dynamics and Monte Carlo simulation. Experiments are leveraged to guide simulations and simulations to interpret experiments. The work aims to build a thermodynamic understanding for key processes in the form of free energy pathways that eschew classical nucleation theory assumptions in out-of-equilibrium systems.This research program engages undergraduates from Morgan State University, a nearby HBCU, to foster the success of a newly emerging 3+2 program that opens new pathways into materials-related engineering majors. A workshop on “Extreme Vacancy Engineering” is also anticipated to promote an emerging field of materials processing and designThis 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.

非技术总结轻质金属合金制造的创新工艺通过高效生产新材料来促进公共福利并确保国防安全，这些新材料在从车辆和防护设备到太空探索的应用中提供强度而不增加重量。该奖项支持有关原子结构如何响应极端温度和应变条件的基础科学研究，这些条件导致称为空位的缺陷，即金属晶体结构中缺少原子。这项研究推进了对空位为什么以及如何与不同于原生金属的溶质原子聚集在一起，聚集成称为空隙的小气泡并促进强化颗粒形成的理解。使用了多种实验技术：使用带正电荷的颗粒测量缺陷，原子探针揭示不同元素在晶体结构中的位置，使用带负电荷的颗粒测量缺陷。并且电子显微镜图像显示较大尺度的特征，例如空隙。模拟预测空位，溶质和空隙如何相互作用，以更好地解释实验数据。这些模拟还提供了空隙形成的速率如何随温度、空位密度和溶质化学性质和密度而变化的估计。实验数据被用来指导模拟的选择，并检查模拟的有效性。在这个过程中，这项工作提高了模拟能力。这个项目吸引了附近一所历史悠久的黑人大学摩根州立大学的本科生，以促进一个新出现的项目的成功，该项目提供了该大学目前不提供的工程学位。研究人员还计划举办一个“极端空缺工程”workshop.Technical总结拟议的研究计划旨在加快新的轻合金和加工路线的发展，扩大我们的基本理解如何空缺过饱和改变热力学的空缺集群，空缺溶质复合物的形成，和空洞形核的方式，促进溶质集群和金属间化合物沉淀。在一系列组成的合金进行淬火和变形，以提高空位密度在一个可控的方式。分析是使用一个新兴的计算方法，过渡界面采样，加上有针对性的表征，使用正电子湮没光谱，原子探针断层扫描，透射电子显微镜与分子动力学和蒙特卡罗模拟。实验被用来指导模拟和模拟来解释实验。这项工作旨在建立一个热力学理解的自由能途径，避开经典的成核理论假设的形式在非平衡系统的关键过程。这项研究计划从事本科生从摩根州立大学，附近的HBCU，以促进一个新出现的3+2计划，开辟新的途径，以材料相关的工程专业的成功。一个关于“极端空缺工程”的研讨会预计也将促进材料加工和设计的新兴领域。该奖项反映了NSF的法定使命，并被认为值得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来支持。