MSE Colloquium: Robert Williams, Analytical Electron Microscopy to Solve Materials Science Problems

Senior Research Officer for the Center for Electron Microscopy and AnalysiS (CEMAS)

All dates for this event occur in the past.

264 MacQuigg Labs
105 W. Woodruff Ave
Columbus, OH 43210
United States

Abstract

The facilities and expertise provided in the previous CEOF, and now housed within CEMAS, provide a unique opportunity to expand the classical definition of analytical electron microscopy (AEM); as well as, develop new techniques and fundamental understanding as we move toward more quantitative characterization to provide more precise metrics for incorporation into Integrated Computational Materials (Science and) Engineering (ICME) models. 

 Historically, AEM has been used to describe the quantification of various spectroscopic signals collected during the interaction of an electron beam with a specimen during transmission electron microscopy (TEM) analysis. Modern AEM should include scanning electron microscopy (SEM) and TEM, but also aberration corrected (S)/TEM, as well as the dual-beam focused ion beam (DB-FIB), all of which are available at CEMAS.

 AEM plays an essential role in two ways, both critical to solving MSE problems. Firstly, it can provide accurate mechanistic details across a range of length scales, from millimeter down to the atomic scale. This data may be used to inform computational models, resulting in increased accuracy, and permitting the models to be more physically relevant. Secondly, AEM may provide experimental validation of the computational predictions.  Additionally, AEM and the integration of modeling and characterization is completely consistent and in concert with the Materials Genome Initiative and the ICME initiative.

 While precise, quantifiable metrics are vital to developing predictive ICME models, it would be a mistake to take the data collected from the microscopes at face value without proper knowledge of where and how the signal was created. Technology has made data collection faster and improved resolution, however, understanding the fine details of electron-solid interaction has become more critical to accurate analysis, particularly, when attempting to use electrons to characterize atomic columns, both spatially and chemically.  Just as we need modeling for prediction and guidance in ICME, AEM need physics based modeling for comparison and quantification.

 Results will be presented showing how AEM has been used to characterize Ti alloys across various length scales and reveal both structural and chemical data providing insight into the microstructural evolution under various thermo-mechanical processing routes. In the process of solving MSE problems with AEM, new techniques are developed and often the fundamental knowledge of the technique is lacking, incorporation of new techniques and fundamental exploration of those techniques will be discussed. 

Bio

Robert received his B.S. in Materials Science and Engineering From Virginia Tech and his M.S. and Ph.D in MSE from The Ohio State University.  During this time Robert worked with the first DB-FIB in academia developing 3D serial sectioning on Ti-alloys as well as TEM sample preparation techniques.  This dictated TEM characterization to better understand the effects of ion milling on EBSD and TEM specimens.  Robert’s thesis work revolved around characterizing the structural and chemical transformation of the omega phase in Ti-Mo alloys by aberration corrected STEM.  Following his thesis and post-doc, Robert was briefly a Research Assistant Professor with University of North Texas before rejoining the MSE department at OSU as the inorganic senior research officer for CEMAS. Robert’s current research has been focused on advanced characterization using the Titan (S)/TEM’s across a range of materials, as well as further pursuit of understanding nano-scale instabilities in titanium alloys for effective manipulation of their properties.