Electron Microscopy:

Novel approaches to understanding microstructural evolution, transport behavior and mechanical properties

Nearly all of our research projects leverage advanced microscopy tools. Below are a few that highlight novel or advanced techniques.

Understanding Short-range Order in Austenitic Steels for use in Hydrogen-Facing Applications

Electron diffuse scattering caused by short-range ordering (SRO) in austenitic steels has been observed using traditional selected area electron diffraction. However, such technique struggles to differentiate diffuse scattering signals stem from different types of SROs (heterogeneous and homogeneous SRO) in the system and thus limits the complete understanding of SRO behaviors. In this work, we demonstrate a procedure utilizing Scanning Electron Nanobeam Diffraction (or 4D-STEM) method and a basic Fluctuation Electron Microscopy technique, variance map, to analyze different type of SROs in a solution treated austenitic steel. The combination of 4D-STEM and variance map techniques enables SRO domain identification and deconvolution of homogeneous and heterogeneous SRO diffuse scattering.

Ion radiation assisted evolution in ceramics

Radiation induced sintering of YSZ nanoparticles at room temperature. Data collected using the I3TEM facilities through the Center for Innovative Nanotechnology (CINT) at Sandia National Laboratory.

We have numerous efforts investigating ion-matter interactions within ceramic systems including the study of radiation enhanced diffusion (RED) via in situ sintering experiments, the efficacy of pores as invariant defect sinks, radiation-induced ordering behaviors and the role of residual order on the amorphization and recyrstallization behavior of oxides.

Deformation mechanisms in high performance ceramics

Comparison of microcrystal deformation behavior in ceria-titania stabilized tetragonal zirconia grains of different orientations.

In situ deformation and advanced application of orientation mapping are at the center of our efforts to understand the mechanical behavior of ferroelastic, polycrystalline ceramics.

Complete efforts studying in situ phase transformation and oxidation behavior