Marc De Graef

Professor and co-director of the J. Earle and Mary Roberts Materials Characterization Laboratory, Carnegie Mellon University

Abstract

In this presentation, I will first review briefly some of the ongoing work in my research group at Carnegie Mellon University. This work focuses on two major areas: magnetic materials, as studied by Lorentz microscopy techniques, and 3-D materials characterization using a variety of experimental modalities.  Two topics will be covered in more depth: (1) the concept of “forward modeling” as a necessary paradigm for quantitative materials characterization, and (2) how one can describe shapes in a quantitative way, as opposed to saying “those two things look like they have a similar shape.”  The forward modeling part of the presentation will deal mostly with the simulation of dynamical electron back-scatter diffraction (EBSD) patterns.  We have developed a new approach that merges dynamical channeling simulations with the results from Monte Carlo trajectory simulations, to obtain more realistic EBSD patterns.  Shape descriptors based on the concept of moment invariants will be introduced next; I will describe how one can make use of moment invariant density maps to correlate shapes observed in 2-D sections to real 3-D shapes.  I will then conclude the presentation with a brief preview of activities during my sabbatical year at OSU.

Bio

Professor De Graef received his BS and MS degrees in physics from the University of Antwerp (Belgium) in 1983, and his Ph.D. in physics from the Catholic University of Leuven (Belgium) in 1989, with a thesis on copper-based shape memory alloys. He then spent three and a half years as a post-doctoral researcher in the Materials Department at the University of California at Santa Barbara before joining Carnegie Mellon in 1993 as an assistant professor. He is currently professor and co-director of the J. Earle and Mary Roberts Materials Characterization Laboratory. Professor De Graef’s research interests lie in the area of microstructural characterization of structural intermetallics and magnetic materials. His current focus is on the development of experimental and modeling techniques for the quantitative study of magnetic domain configurations in a variety of materials, including ferromagnetic shape memory alloys, magnetic thin films, and patterned structures. This study includes a theoretical analysis of the use of shape functions in the computation of shape-dependent material properties. A second research focus is on the acquisition and representation of the three-dimensional character of microstructures. Work in this area includes development of experimental and numerical techniques to extract quantitative 3-D data from serial sectioning and tomography experiments.