MSE Distinguished Alumnus Colloquium: Brent Adams, Structure-Property Relationships for Polycrystals: Twenty Five Years of Development of Automated electron Backscattered Diffreaction (EBSD) Methods

Emeritus Professor, Brigham Young University

All dates for this event occur in the past.

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

Abstract

My fascination with polycrystalline materials, and with structure-property relationships that provide bounds and estimates for their mechanical properties, began during my doctoral program at The Ohio State University, nearly forty years ago.  Available properties relationships dictated the need for statistical information on local state distributions.  In 1987 the scientific community was inspired by two new experimental approaches that had the potential to acquire large numbers of the needed local state statistics – the synchrotron x-ray diffraction, and electron backscatter diffraction (EBSD) methods.  Within five years automated EBSD methods would be introduced that would dramatically expand access to the spatially-specific lattice orientation statistics required by the available homogenization relations for single phase polycrystals.  This presentation is about the evolution of EBSD-based electron microscopy over the past ~25 years – since the first automated systems were introduced.

This presentation will briefly retrace the requirements of Hill-Paul bounds on defect-insensitive linear properties.  Emerging from low-contrast solutions to the equilibrium equations is the need for point correlation statistics on local state polycrystalline microstructure. Similar requirements emerge from consideration of the Taylor bound on initial yield properties.  

The main part of the lecture will be prospective, focusing on recent advances for EBSD methods to dramatically broaden the accessible dimensions of the local state space.  This began with demonstrated partial recovery of the Nye dislocation tensor from local gradients in the orientation field.  More recent advances in EBSD, known as high-resolution EBSD (HREBSD), are described. These dramatically improved the angular resolution in recoveries of orientation gradients.  

It is shown that when data analysis is coupled with the equilibrium equation, and the traction free surface condition applicable to sectioned samples, that the full Nye tensor can be recovered from HREBSD data.  The analysis required is named micromechanical stereo-inference.  When coupled with planar scanning strategies, a useful dislocation microscopy becomes available. Implication for advancing structure-properties relationships into the realm of defect-sensitive properties is discussed.

Bio

 

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Dr. Brent Adams

Brent L. Adams received his bachelor’s degree in physics at the University of Utah in 1974.  After a brief time of graduate study in Astrophysics at The Ohio State University, he began his graduate studies in Metallurgical Engineering. He completed an M.S. in 1976, and took full-time employment at the Lynchburg Research Center of Babcock and Wilcox Co.  While conducting research there on anisotropic creep of zirconium alloys used in nuclear reactor cores, he completed his Ph.D. at The Ohio State University in 1979.  In 1979-1980 he studied swelling and other radiation effects in steels at the DOE Hanford facility in Richland WA.  His academic career began in the Materials Science Department of the University of Florida in 1980.  He would later accept academic appointments at Brigham Young University, Carnegie Mellon University, and Yale University.  He retired in 2012 after holding the position as Dusenberry Professor of Mechanical Engineering at Brigham Young University for ten years.

During his career, Professor Adams published over 200 scientific articles and several books.  He is perhaps best known for his pioneering work with his students in developing Orientation Imaging Microscopy.  That work, commercialized in 1995, dramatically enhanced the characterization capabilities of electron microscopy, and is now used as a standard method in microscopy around the world.

He was the recipient of an NSF Presidential Young Investigator Award in 1985. He is twice the recipient of the ASM International Henry Marion Howe Medal; he is also twice the recipient of the TMS-AIME Champion Mathewson Medal.  He was elected Fellow in ASM International in 2004.  In 2011 he received the Bunge Award from The International Conference on Textures of Materials for his lifetime achievements in the field of texture and microstructure. In 2008 he was honored with the Governor’s Medal of Science and Technology by the State of Utah.

He has been married to Hilary Trunnell for 44 years, they are the parents of three sons, Christian, Isaac and Benjamin, and they now have six (well above average) grandchildren.  Since his retirement in 2012, Brent and Hilary have served two full time missions for their church – the first in St. Petersburg Russia, and the second in Manchester NH.  They now make their home in red-rock country near Cedar City UT.