Innovation in High Energy Diffraction Microscopy Adds New Insights to Material Deformation and Failure

A team of researchers from the Air Force Research Laboratory, Argonne National Laboratory, Lawrence Livermore National Laboratory, Carnegie Mellon University, Petra III (Germany), PulseRay, and Cornell University have developed a revolutionary experimental capability using high energy synchrotron x-ray techniques to non-destructively measure the internal structure and micro-mechanical state of deforming polycrystalline solids. The team developed a unique rotation and axial motion system which allows traditional mechanical testing methods to be combined concurrently for the first time with near and far field high energy diffraction microscopy (HEDM) techniques as well as micro-computed tomography. This enables the in situ observation of the three-dimensional grain structure including crystallographic orientations with sub-grain resolution, the elastic strain (stress with knowledge of elastic constants) state of individual grains or individual layers of grains, and the formation of voids and cracks. When combined in situ with mechanical loading, this provides an unprecedented capability to probe the evolution of the internal state of the material while subjected to external stimuli.

The mechanical response of solid materials is governed by deformation processes over many length scales. Over the last 50 years a number of physics-based models have been developed to describe the performance of engineering materials. However, only limited adoption of these tools has occurred in engineering practice because of a lack of experimental data at the scale of the models, preventing the validation of their performance. This new capability will provide incredibly rich datasets to validate and further develop deformation models which are sensitive to the local microstructure. This may lead to revolutionary developments of microstructure based property and life prediction models. Having validated models of materials behavior will allow materials scientists and engineers to much more rapidly understand and improve the mechanical performance of structural materials and speed their development and deployment for improved product performance.

This research was funded by the Air Force Research Laboratory and the National Science Foundation through the Cornell High Energy Synchrotron Source. A portion of the research was conducted at the Advanced Photon Source, a Department of Energy Office of Science User Facility.