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

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

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.