May/June_AMP_Digital

1 0 A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 0 CREATING 3D MAPS OF 2D MATERIALS Led by UCLA, Calif., a research team has successfully created experi- mental 3D maps of the atoms in a 2D material. Collaborators on the team included researchers from Harvard Uni- versity, Cambridge, Mass.; Oak Ridge National Laboratory, Tenn.; and Rice University, Houston. The researchers examined a single layer of molybdenum disulfide, a fre- quently studied 2D material. To analyze the material, the researchers used a new technology they developed based on scanning transmission electron microscopy. The team then devised a technique called scanning atomic elec- tron tomography, which produces 3D images by capturing a sample at multi- ple angles as it rotates. The resulting images enabled the researchers to inspect the sample’s 3D structure to a precision of 4 picometers. TESTING | CHARACTERIZATION OBSERVING GRAIN BOUNDARY TRANSFORMATIONS IN METAL Scientists at the Max Planck Insti- tute for Iron Research (MPIE), Ger- many, have found a new way to directly observe grain boundary transitions during experiments. The team worked with colleagues at Lawrence Livermore National Laboratory (LLNL), Livermore, Calif., who modeled the grain bound- ary transformations. The MPIE team also used the atomic resolution micro- scopes to directly visualize the trans- forming interfaces. The collaborative research team analyzed thin films of pure cop- per by atomic-resolved transmission electron microscopy. Using this technique, they unlocked the grain boundary pha- ses and proofed their coexistence with atomic precision. To model the grain boundary phases, LLNL researchers used a novel grain boundary struc- ture search algorithm. In addition, their finite- temperature molecular dynamics simulations ex- plored the transforma- tion kinetics. The predic- ted structures not only perfectly resemble the experimental observa- tions but also demon- strate that the grain boundary phases can transform into each other by changing temperature or stress. The simulations indicate that the grain boundary phase junc- tion, a novel line defect that has not been considered previously, is rate controlling. The scientists aim to widen the current observations to experiments done at different temperatures, under stress, and in the presence of impurities to establish a complete understanding of these phase transformations. www. mpie.de/2281/en, llnl.gov. Atomic resolution scanning transmission electron microscopy image of a grain boundary phase transformation in elemental copper. Courtesy of Christian Liebscher/Max-Planck-Institut für Eisenforschung GmbH. The 3D atomic coordinates of molybdenum (blue), sulfur (yellow) and added rhenium (orange) are shown, with a 2D image visible underneath. Courtesy of University of California, Los Angeles. Rimkus Consulting Group, Inc., Houston, a worldwide provider of forensic engineering and consulting services, has acquired North Carolina-based Metallurgical Technologies, Inc. (Met-Tech), Mooresville, a metallurgical analysis and testing laboratory that specializes in rapid response forensic materials engineering. Rimkus operates more than 60 offices across the U.S., Canada, and the U.K., with a consulting network of more than 500 experts. rimkus.com . BRIEF