Special Materials Science & Engineering Seminar
Date: March 28, 2013 from 11:00 am to 12:00 pm EDT
Location: Columbia University
Morningside Campus
210 S.W. Mudd, APAM Conference Room
Contact: For further information regarding this event, please contact APAM Department by sending email to seasinfo.apam@columbia.edu or by calling 212-854-4457.
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Bookmark and Share Muriel Veron, Grenoble-INP

"Crystal Orientation mapping in the Transmission Electron Microscope: Introduction to ACOM and ASTAR system"

EBSD (electron back scatter diffraction) is now a well-known technique that allows orientation and phase mapping using an SEM (scanning electron microscope). ACOM (automated crystal orientation mapping) and ASTAR (in this case, we couple the mapping with the precession) tools were developed recently for the TEM (transmission electron microscope) with good reliability and reasonable acquisition times. Both techniques allow orientation and phase mapping of a TEM specimen, with a good accuracy. This is done in two steps: first the diffraction patterns are acquired and are stored, and, second, the patterns are analyzed using a template matching technique A sketch of the device is presented in figure 1, showing external diffraction pattern acquisition camera, and typical results in terms of orientation and phase recognition.


 

Figure 1: ACOM and ASTAR principle : acquisition of electron diffraction pattern on a ROI, identification, and results.

Phase and orientation mapping based on classical diffraction patterns in the TEM was first developed to answer specific questions with regards to heavily-deformed materials. Indeed, Kikuchi patterns used in EBSD are faded for deformed materials and cannot be used to give grain sizes in such materials, and classical bright-field contrast in the TEM is too complex to be interpreted. Depending on the transmission electron microscope setting (FEG or LaB6), orientation and phase identification in a region of interest up to 10um2 is performed with a step size ranging from 1nm to 20nm.  In this seminar, the method and several results will be presented to illustrate the potential of the technique: Grain size analysis in heavily deformed materials and Cu interconnection lines, and determination of recrystallization mechanisms in a ferritic stainless steels will be presented.For a better precision  analysis and recognition of complex structure, precession is used to improve quality of acquired diffraction patterns and resulting high resolution orientation-phase maps.

Joint work with Edgar RAUCH, Daniel Bultreys and Stavros Nicolopoulos

References

E. Rauch, M. Veron, J. Portillo, D. Bultreys, Y. Maniette, and S. Nicolopoulos, "Automatic Crystal Orientation and Phase Mapping in TEM by Precession Diffraction", Microscopy and Analysis, Issue 93, pp. S5-S8, November 2008.

Biography

Muriel Veron received her Engineering degree and her PhD. in Material Science and Engineering from Grenoble-INP, France. After completing her PhD in 1995, she joined the department of Materials Science and Engineering from McMaster University, Canada as a Postdoctoral Research Associate. In 1996 she moved back to France to take an Assistant Professor position at Grenoble-INP and SIMaP Laboratory (Material Science and Process Laboratory). She was made a Professor in 2008. Since 2009 she holds the post of Deputy Director of engineering school Phelma, with 1200 students and important international collaborations. In July 2011, she was awarded APERAM Rene Castro Prize for her contribution in steel phase transformations and alloy design. In the Metal Physics department from SIMaP, her research focuses on the coupling between microstructure and mechanical properties. She works closely with industrial collaborators on fundamental and applied topics. Muriel Veron has contributed significantly to the development of TEM automated orientation mapping in association with the pioneering work of Dr. Edgar Rauch (CNRS), allowing to map orientations and phases at the nanometer scale and providing the scientific and industrial communities with a new and powerful tool to investigate materials. The applications cover metallurgic materials, nanoelectronic devices, geological samples, even TEM beam sensitive materials such as polymers with future biological sciences applications envisaged. 

Host: Katayun Barmak