Pantleon, W | Search NASA

DOE OSTI2012

High-energy diffraction microscopy at the advanced photon source

The status of the High Energy Diffraction Microscopy (HEDM) program at the 1-ID beam line of the Advanced Photon Source is reported. HEDM applies high energy synchrotron radiation for the grain and sub-grain scale structural and mechanical characterization of polycrystalline bulk materials in situ during thermomechanical loading. Case studies demonstrate the mapping of grain boundary topology, the evaluation of stress tensors of individual grains during tensile deformation and comparison to a finite element modeling simulation, and the characterization of evolving dislocation structure. Complementary information is obtained by post mortem electron microscopy on the same sample volume previously investigated by HEDM.

43 PARTICLE ACCELERATORS↗

DOE OSTI2011

4D Characterization of Metals by 3DXRD

The status of 3DXRD microscopy is reviewed, with a special view to applications in metallurgy. Various approaches are compared in terms of performance. In addition several recent advances are presented, such as a 3D grain map with an unprecedented spatial resolution of 500 nm, first results from the commissioning of a novel 3D detector set-up and a validation of the box-scan procedure. Three-Dimensional X-Ray Diffraction (3DXRD) is a novel technique, aiming at a fast and nondestructive characterization of the individual crystalline elements within mm-sized polycrystalline specimens. It is based on two principles: the use of highly penetrating hard X-rays from a synchrotron source (x-ray energies in the range 20-100 keV) and the application of 'tomographic' reconstruction algorithms for the analysis of the diffraction data. In favourable cases, the position, morphology, phase, and crystallographic orientation can be derived for hundreds of elements simultaneously as well as their elastic strains. Furthermore, the dynamics of the individual elements can be monitored during typical processes such as deformation or annealing. Hence, for the first time information on the interaction between elements can be obtained directly. The provision of such data is vital in order to extend beyond state-of-art structural models.

36 MATERIALS SCIENCE↗