MSE Seminar Series: Development and utilization of advanced electron microscopy techniques
Speaker: Asher C. Leff, Research Scientist, U.S. Army Research Laboratory
Title: Development and utilization of advanced electron microscopy techniques for unique insight into materials fabrication, processing, and performance
Scanning and transmission electron microscopy are powerful tools for the characterization of materials that have been utilized for decades. Recently, there have been significant developments in both the microscopes themselves and the detection and analysis techniques that enhance their capabilities. In this talk, Dr. Leff will discuss a survey of advanced electron microscopy techniques including precession electron diffraction, Nye tensor dislocation density mapping, direct electron detection-electron energy loss spectroscopy, in situ heating, deformation, and ion irradiation, and spherical aberration correction. Each of these tools provide the ability to gain unique insights into material fabrication, processing, and performance. Topics covered will include the evolution of twin microstructures in Cu, the nature of deformation in nanocrystalline Fe, the formation of precipitates in Al-Mg and Ni-Ti alloys, the evolution of radiation-induced defects in Fe and steel, and MBE growth of III-V semiconductors.
Asher Leff received his BS and MS degrees in Materials Science & Engineering from Drexel University in 2013 before completing his PhD in Materials Science & Engineering at Drexel in 2017. During his PhD worked for Mitra Taheri’s Dynamic Characterization Group where he specialized in in situ microscopy techniques and the development of new TEM acquisition and analysis methods including pioneering work on direct-electron-detection electron energy loss spectroscopy and quantitative methodologies for extracting dislocation densities from spatially mapped crystallographic orientation data. Since August of 2017 Asher has worked as the TEM scientist for ARL’s Sensors and Electron Devices Directorate, where he has worked on a variety of applications to support Army materials research. His primary research interests are the utilization of reversible solid-solid phase transformations to manage thermal transients and the development of 3D device structures for advanced electrical energy storage.