Grain scale in situ observations on deformation twinning with reciprocal
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Title: Grain scale in situ observations on deformation twinning with reciprocal

Speaker: Dr. Can Aydiner

Date/Time: November 18, 2015 Wednesday, 13:40 - 14:30 

Place: FENS L055

AbstractIn materials science, reciprocal space diffraction techniques primarily yield lattice (elastic) strain whereas real space techniques like microscopy yield total strains. This is only one of the ways the two measurement modes are complementary. In this talk, twinning in hexagonal close packed Magnesium is examined with subsequent application of a high-end synchrotron x-ray diffraction (SXRD) technique (reciprocal space) [1], followed by a comprehensive microscopic digital image correlation (real space) measurement that covers thousands of grains with intragrain spatial resolution [2]. In the case of SXRD, implemented in 1-ID beamline, Argonne National Laboratory, a single grain’s interaction with its own emerging twin band is directly observed in terms of lattice strains measured from both. With microscopic DIC, on the other hand, the complex strain fields that emerge at the onset of extensive deformation twinning has been investigated. Here, a two camera setup has been used to yield full-field deformation maps on two orthogonal faces of a gradually strained prismatic sample. The samples in both studies are cut off from a rolled plate to favor profuse twinning. The explosive and heterogeneous nature of mechanical fields that form upon twinning is detailed from both perspectives. [1] C. C. Aydıner, J. V. Bernier, B. Clausen, U. Lienert, C. N. Tome, D. W. Brown, Physical Review B, 2008, 024113. (doi: 10.1103/PhysRevB.80.024113). [2] Aydıner, C. C. ; Telemez, M. A, International Journal of Plasticity 2014, 56, 203-218.

Bio: Dr. C. Can Aydiner has taken his B.S. degree in 1998 from Middle East Technical University (Ankara,Turkey), Department of Mechanical Engineering. He continued his education at the California Institute of Technology (Pasadena, CA), receiving his M.S. in Applied Mechanics (1999) and subsequently Ph.D. in Applied Mechanics with Materials Science Minor (2004). Dr. Aydıner’s Ph.D. thesis investigated residual stress formation in bulk metallic glasses during fast quench. Here, the slitting technique was employed to measure the stresses in these opaque and amorphous materials that did not admit any other technique. Dr. Aydiner conducted in situ synchrotron X-ray and neutron diffraction experiments at Los Alamos, Argonne, Lawrence Berkeley and Brookhaven National Laboratories on many material systems that include metallic glass composites, ferroelectrics, and thermal barrier coatings. After a brief postdoctoral tenure in Iowa State University, Department of Materials Science and Engineering, he was granted a Director’s Postdoctoral Fellowship at Los Alamos National Laboratory. At this stage, the research focus was on micromechanical investigations of nano-grained materials, metal nanolayers and twinning phenomena in HCPs. From 2009 onwards, Dr. Aydiner has been at Bogazici University and is currently Associate Professor of Mechanical Engineering. Current research interests are multi-scale polycrystal modeling and in situ crystallite level investigations with the full-field deformation measurement technique of digital image correlation.