Harnessing Abnormal Grain Growth for the Production of Single Crystals

利用异常晶粒生长来生产单晶

• 批准号: 2003719
• 负责人: Katsuyo Thornton
• 金额: $ 17.6万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003719&HistoricalAwards=false
• 关键词: Harnessing; Abnormal; Grain; Growth; Production

Non-technical summary:Most engineering materials are commonly found in polycrystalline form, in which a solid consists of many tiny crystals with different orientations. In some cases, superior properties can be achieved when the material is made in a single crystal form, as in the case for jet-engine turbine blades and solar cells. However, single crystals are expensive and time-consuming to produce. Recently researchers have developed a method for the production of single crystals by exploiting abnormal grain growth induced by cyclic heat treatment, in which a metal alloy is heated and cooled repeatedly. During abnormal grain growth, a few grains preferentially grow by engulfing the neighboring grains. The goal of this project is to discover why and how this process occurs. The project integrates emergent research in structural characterization and simulations of grain growth, capitalizing on our ability to watch the evolution of the grain network in real-time, and leveraging high performance computing resources to simulate microstructural evolution. Developing this fundamental understanding of abnormal grain growth could lead to a paradigm shift in the manufacture of single-crystalline materials, and therefore it promotes global competitiveness in manufacturing and technology and national prosperity. The project also promotes the development of a highly trained future workforce; two graduate students are trained in state-of-the-art techniques in experiments, modeling, simulations, and data analysis. Outreach activities are carried out through the Females Excelling More in the Math, Engineering, and the Sciences program and Washtenaw Elementary Science Olympiad and include a virtual reality demonstration that allows students to walk through an evolving microstructure during heat treatment. Technical summary:A cyclic heat treatment that induces abnormal grain growth holds promise for solid-state processing of single crystals and otherwise large-grained materials. However, its full potential has not been realized due to the poor understanding of the mechanisms underlying the process. The objective of this project is to advance the science governing the growth of the abnormal grains during cyclic thermal treatment. The following fundamental questions are addressed: What is the mechanism by which abnormal grain growth is initiated during a cyclic heat treatment? Which grains are most likely to become abnormal and what are their microstructural signatures? How does the abnormal grain grow into new microstructural neighborhoods? To answer these questions, emergent research in structural characterization, phase-field and phase-field-crystal modeling, and graph theory methods are synergistically integrated. High-resolution synchrotron-based X-ray diffraction microscopy is utilized to visualize and quantify the evolution of the grain and subgrain network in real-time and also enable microstructural evolution simulations based on the measured space-, time-, and orientation-resolved datasets as initial conditions. The resulting high-dimensional data is then distilled into a network model that succinctly describes the microstructure and the local driving forces for grain boundary motion. Scientific understanding of abnormal grain growth upon thermal cycling will ultimately inform the process design of single-crystal fabrication.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：大多数工程材料通常以多晶形式找到，其中固体由许多具有不同方向的微小晶体组成。 在某些情况下，当材料以单晶形式制成时，可以实现出色的性质，例如喷气引擎涡轮叶片和太阳能电池。 但是，单晶很昂贵且耗时。 最近，研究人员通过利用循环热处理引起的异常谷物生长来开发一种用于生产单晶的方法，其中金属合金被反复加热并冷却。 在异常的谷物生长过程中，通过吞没相邻的谷物优先生长一些谷物。 该项目的目的是发现该过程的发生原因和方式。该项目在结构表征和谷物生长的模拟中综合了新兴研究，利用了我们观察谷物网络实时演变的能力，并利用高性能计算资源来模拟微观结构的演变。 对异常谷物生长的这种基本了解可能会导致单晶材料制造的范式转变，因此它促进了制造业和技术和国家繁荣方面的全球竞争力。 该项目还促进了训练有素的未来劳动力的发展；两名研究生接受了实验，建模，模拟和数据分析的最先进技术培训。 外展活动是通过女性在数学，工程学和科学课程和Washtenaw基础科学奥林匹克方面表现出色的女性进行的，其中包括一个虚拟现实演示，使学生可以在热处理期间经历不断发展的微观结构。 技术摘要：一种循环热处理，诱导异常的谷物生长有望单晶体和其他大颗粒材料的固态加工。 但是，由于对过程基础机制的理解不足，其全部潜力尚未实现。 该项目的目的是推进循环热处理期间异常晶粒生长的科学。 解决了以下基本问题：在循环热处理期间启动异常谷物生长的机制是什么？ 哪些谷物最有可能变得异常，它们的微结构特征是什么？ 异常的谷物如何生长到新的微观结构社区？ 为了回答这些问题，在结构表征，相位场和相位晶体建模以及图理论方法方面进行了紧急研究。 基于高分辨率同步加速器的X射线衍射显微镜用于实时可视化和量化谷物和亚晶粒网络的演化，还可以基于测得的空间，时间和方向分辨数据集作为初始条件，从而实现微结构演化模拟。 然后将所得的高维数据提炼成网络模型，该模型简要描述了微观结构和局部驱动力以进行晶粒边界运动。 热循环时对异常谷物生长的科学理解最终将为单晶制造的过程设计提供依据。该奖项反映了NSF的法定任务，并且使用基金会的知识分子优点和更广泛的影响评估标准，认为值得通过评估值得支持。

项目成果

Anomalous strain-energy-driven macroscale translation of grains during nonisothermal annealing

非等温退火过程中异常应变能驱动的晶粒宏观尺度平移

• DOI: 10.13011/m3-tnfb-4654
• 发表时间: 2022
• 期刊: Materials Commons
• 作者: Kang, Jiwoong