HOW SPATIALLY RESOLVED THREE-DIMENSIONAL X-RAY MICRODIFFRACTION AND
FLUORESCENCE PROVIDE A FUNDAMENTALLY NEW UNDERSTANDING OF MESOSCALE
DYNAMICS IN MATERIALS
Gene E. Ice
Corporate Fellow/Group Leader
Oak Ridge National Laboratory
Metals and Ceramics Division
X-ray Research and Applications Group
PO Box 2008
Oak Ridge, TN 37831-6118
The characterization of materials begins with three questions: what is the elemental
concentration/distribution? what is the average atomic (crystallographic) structure? and what
are the defects? Emerging x-ray microbeam measurements can nondestructively address all
three questions with unprecedented precision. In particular, virtually all materials have
properties determined by atomic and mesoscopic inhomogeneities and defect distributions.
These distributions can be studied by a variety of established x-ray spectroscopic and
diffraction methods but the most highly developed x-ray analysis methods require nearlyperfect single crystals. What is needed is a way to probe intra- and inter-granular defects and
structures with sufficient spatial resolution to resolve regions with local “single-crystal like”
structure. Here we describe emerging x-ray microbeam techniques that bring powerful x-ray
diffraction and spectroscopy methods long reserved for large samples to the subgrain scale of
polycrystalline materials. In particular, we show how monochromatic, polychromatic, and
tunable monochromatic measurements on small sample volumes can reveal their local atomic
and mesoscopic defect structures. This emerging revolution in materials characterization is
certain to address long-standing issues of materials behavior.