Nanosegregation, microtexture and the control of brittle failure David B. Williams and Masashi Watanabe, Lehigh University, DMR Fig. 1 (left) A schematic diagram of a STEM-based diffraction imaging method. Fig. 2 (bottom) A grain map from a Y-doped ZrO 2 thin-specimen obtained by STEM-based DI method. Intellectual Merit Development of a high resolution orientation analysis method in STEM Orientation information of materials is now routinely gathered in scanning electron microscopy (SEM) by the electron backscattering diffraction (EBSD) method. However, the spatial resolution of SEM-EBSD is limited to typically ~30 nm, and hence it is not straightforward to correlate any local chemical or structural changes on the nanometer scale, which are regularly examined in (scanning) transmission electron microscopy ((S)TEM). We have developed a new approach called “STEM-based diffraction imaging”, which allows us to record automatically a series of convergent-beam electron diffraction (CBED) patterns in the STEM mode (Fig. 1). This method requires much larger computer memory available in typical PC because the diffraction image dataset contains 4 dimensional space (spatially 2D and angularly 2D). However, we developed several schemes to handle such larger datasets in terms of data acquisition and analysis. From the diffraction image dataset, orientation information such as a grain map and related misorientation between grains can be extracted. The first grain map obtained from Y-doped ZrO2 by the diffraction- imaging method is shown with the CBED patterns from each grain in Fig. 2. By applying this new approach, a grain-orientation map can, in principle, be formed with much better spatial resolution (below 1 nm in an aberration-corrected STEM).

Nanosegregation, microtexture and the control of brittle failure David B. Williams and Masashi Watanabe, Lehigh University, DMR Broader Impact Atom probe tomography by remote control We have characterized fine-scale precipitates in a Ni- based superalloy using an Imago Local Electrode Atom Probe (LEAP) system located at University of Sydney (collaborating with Prof. Simon Ringer and Dr. David Saxey) through remote control from Lehigh University. The atom-probe system is designed to be controlled remotely and we demonstrated the remote operation connected via fast internet. Figure 1 shows a screen shot of the alignment of an atom-probe specimen in Sydney remotely controlled from a PC at Lehigh. The results obtained from this experiment are shown in Fig. 2, a: Ti composition distribution (red) reconstructed from the atom-probe dataset, b and c are composition- line profiles between the matrix and a  ’ precipitate. As summarized in our previous research highlight (2006), an aberration-corrected JEM-2200FS STEM at Lehigh can also be remotely controlled. Therefore, we can access both of our instruments from other sites and these atomic-scale characterizations can be carried out around the world through the internet, opening new possibilities for international scientific collaboration in the 21st century. In addition, we received a best-poster award for this work in “The 16 th International Microscopy Congress” held in Sapporo, Japan (September 2006). Fig. 1 (left) An image showing the remote operation of U. Sydney’s atom probe instrument from Lehigh. Fig. 2 (bottom) A three- dimensional APT reconstruction (a) with a 5% Ti isoconcentration surface shown in red. One- dimensional composition profiles from the matrix to coarse (b) and fine (c) precipitates respectively.