Recent Breakthroughs in Orientation Microscopy across Length Scales

Dr. Peter C. Collins, Iowa State University
February 19, 2018 at 11:00 am
206 Crow
Event Description 

Orientation microscopy has traditionally been synonymous with an SEM-based technique that relies upon the generation and collection of electron backscattered diffraction patterns to characterize the spatial distribution of crystal orientation, providing "OIM" micrographs and corresponding texture plots. Over the years, powerful analytical techniques have been developed to use this information to characterize everything from texture to grain boundary character distributions. But, the fundamental aspects of the signal generation has necessarily restricted its applicability to problems where the resolution is not better than ~30nm, and the areas of interest are no larger than ~1mm2. This leaves problems which require superior resolution or which require analysis of larger areas largely unexplored. This talk will present recent breakthroughs on precession electron diffraction (PED), a transmission electron diffraction technique with resolutions of ~2nm, as well as a new technique (spatially resolved acoustic spectroscopy (SRAS)) that relies upon surface acoustic waves (SAWs) that is capable of characterizing ~15,000mm2. We will show that this opens upon important research topics, such as spatially mapping out dislocation densities or the quantification of microstruturally textured regions (MTRs).