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的形式存在，其中固体由许多不同取向的微小晶体组成。在某些情况下，当材料以单晶形式制成时，可以获得更好的性能，就像喷气发动机涡轮叶片和太阳能电池的情况一样。然而，单晶的生产既昂贵又耗时。最近，研究人员开发了一种利用循环热处理引起的异常晶粒长大来生产单晶的方法，即金属合金反复加热和冷却。在异常生长过程中，少数颗粒通过吞噬相邻颗粒优先生长。这个项目的目标是发现这一过程发生的原因和方式。该项目集成了结构表征和颗粒生长模拟方面的新兴研究，利用我们实时观察颗粒网络演变的能力，并利用高性能计算资源来模拟微观结构演变。发展这种对异常晶粒生长的基本理解可能会导致单晶材料制造的范式转变，从而促进制造和技术方面的全球竞争力和国家繁荣。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、模拟和数据分析方面的最新技术培训。外展活动是通过在数学、工程和科学项目以及华盛顿初级科学奥林匹克竞赛中表现更出色的女性来进行的，其中包括一个虚拟现实演示，允许学生在热处理过程中浏览不断演变的微观结构。技术概述：一种导致异常晶粒长大的循环热处理有望用于单晶和其他大颗粒材料的固态加工。然而，由于对这一进程背后的机制了解不深，它的全部潜力尚未实现。本项目的目的是为了促进控制循环热处理过程中异常晶粒生长的科学。解决了以下基本问题：在循环热处理过程中，启动异常晶粒长大的机制是什么？哪些颗粒最有可能变得异常，它们的微观结构特征是什么？异常颗粒是如何生长成新的微观结构的？为了回答这些问题，结构表征、相场和相场-晶体建模以及图论方法的新兴研究被协同地整合在一起。基于同步加速器的高分辨率X射线衍射显微镜被用来实时可视化和量化颗粒和亚颗粒网络的演变，并能够基于测量的空间、时间和取向分辨的数据集作为初始条件来模拟微观结构的演变。由此产生的高维数据被提炼成一个网络模型，该模型简洁地描述了晶界运动的微观结构和局部驱动力。对热循环过程中异常颗粒生长的科学理解最终将为单晶制造的工艺设计提供信息。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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