CAREER: Nanoscale Order in Metallic Glass Investigated with Electron Imaging and Diffraction

这个授予威斯康星大学麦迪逊分校的职业奖项是利用起伏电子显微镜、电子衍射、电子能谱和原子结构建模来研究金属玻璃中的纳米级构型。涨落电子显微镜对无序材料结构顺序的细微变化非常敏感。由于金属玻璃的特殊和有用的性质往往归因于某种程度的纳米级原子有序化，这些研究可能会为寻找具有更好性能的新的金属玻璃提供帮助。在进行了高Al含量玻璃的初步实验后，将对大块金属玻璃的有序性和大块玻璃合金的液态进行实验研究。该项目的短期目标是了解铝基玻璃结构控制去玻璃化的各个方面，以及它们如何随着工艺的变化而改变。长期的目标是对金属玻璃中的堆积和局域有序有一个普遍的了解，并了解它们的纳米级初级再结晶。为了使学生掌握在纳米尺度上进行定量测量的工具，将开发一门新的定量电子显微镜课程，使用电子散射的计算机模拟和电子显微镜数据的数字分析。还将开发一个教学模块，允许中学生和教师通过研究硬球的包装来实验探索金属晶体和玻璃的原子结构。该项目将支持使用起伏电子显微镜这一先进的电子显微镜技术来测量一纳米尺度的金属玻璃结构的研究。金属玻璃的重量可以非常坚固，或者与通常使用的金属相比，可以制造出非常好的磁体。然而，由于对它们对原子结构的影响了解不足，定制这些理想性质的尝试一直受到阻碍。该项目提出的措施将有助于了解材料的结构，从而指导新材料的合成。该项目还将支持理科研究生和中学生教育教材的开发。研究生将教授他们进入未来纳米技术大军所需的高级电子显微镜技能。中学生的材料将使用简单的实验来包装坚硬的球体(如罐子里的弹珠)，让学生自己发现指导我们理解金属结构的一般原理。这样做的目的是给学生一种做科学的感觉，而不仅仅是学习科学，从而鼓励他们在以后的生活中追求科学事业。

This Career award to University of Wisconsin Madison is to study nanoscale configuration in metallic glasses using fluctuation electron microscopy, electron diffraction, electron spectroscopy, and atomistic structural modeling. Fluctuation electron microscopy is uniquely sensitive to subtle changes in structural order in disordered materials. Since unusual and useful properties of metallic glass are often attributed to some level of nanoscale atomic ordering, these studies may provide search for new metallic glasses with improved properties. After initial experimental focus on high Al-content glasses, experiments will be carried out to study order in bulk metallic glasses and the liquid state of bulk-glass alloys. The short-term goal of this project is an understanding of aspects of Al-based glass structure that govern devitrification and how they can be changed with processing. The long-term goal is a general understanding of packing and local order in metallic glasses, and to understand their nanoscale primary recrystallization. With a goal to equip students with the tools to make quantitative measurements at the nanoscale, a new curriculum in quantitative electron microscopy will be developed using computer simulations of electron scattering and digital analysis of electron microscopy data. An instructional module will also be developed to allow middle school students and teachers to experimentally explore the atomic structure of metal crystals and glasses by studying the packing of hard-spheres. This project will supports studies using fluctuation electron microscopy, an advanced electron microscopy technique, to measure the structure of metallic glass at length scales of one nanometer. Metallic glasses can be very strong for their weight, or make exceptionally good magnets compared to the metals normally used. However, attempts to tailor those desirable properties have been hampered by insufficient understanding of their effects on the atomic structure. Proposed measurements in this project will help to understand the structure of materials, and therefore guide the synthesis of new materials.This project will also support development of educational materials for educating science graduate students and middle school students. Graduate students will teach them the advanced electron microscopy skills they will need to enter the nanotechnology workforce of the future. The materials for middle school students will use simple experiments in packing of hard spheres (like marbles in a jar) to let students discover for themselves the general principles that guide our understanding of the structure of metals. The goal is to give the students the feeling of doing, rather than just learning about, science, and thereby encouraging them to pursue careers in science later in life.