Papers by Keyword: Grain Rotation

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Authors: Byung Nam Kim, Keijiro Hiraga, Koji Morita, Hidehiro Yoshida
Abstract: When the sliding of the grain boundary containing hexagonal particles is accommodated by grain-boundary diffusion, we evaluate the sliding rate and the stress distribution on the boundary, by taking the particle rotation and the intrinsic boundary viscosity into account. The sliding rate was obtained by the energy-balance method, and the particle-rotation rate by a condition of minimum energy-dissipation. With increasing boundary viscosity, the rotation rate increases and then decreases after a maximum. The sliding rate is enhanced by the particle rotation, and decreases with the boundary viscosity.
Authors: L.A. Barrales-Mora, Jann Erik Brandenburg, Dmitri A. Molodov
Abstract: Molecular dynamics simulations were performed to analyze the curvature-driven shrinkage of individual cylindrical grains with geometrically different boundaries in Al. Grains with <100> tilt and mixed tilt-twist boundaries with the misorientations 5.5°, 16.3°, and 22.6° were simulated. The results revealed that the shrinking grains with tilt boundaries concurrently rotate increasing the misorientation angles, whereas grains with the mixed boundaries did not rotate during their shrinkage. Apparently, the grain boundary geometry/structure has a crucial impact on the observed rotational behavior of the computed grains. The grains with tilt boundaries rotate due to the lack of effectively operating mechanisms for annihilation of edge dislocations, which compose such boundaries. In contrast, for the mixed boundaries composed of edge-screw dislocations the sufficiently fast operating mechanisms of dislocation elimination are available, which facilitates grain shrinkage without rotation.
Authors: Alexander H. King, K.E. Harris
Authors: Tohru Yamasaki, Y. Demizu, Y. Ogino
Authors: Hong Jia Zhang, Enrico Salvati, Chrysanthi Papadaki, Kai Soon Fong, Xu Song, Alexander M. Korsunsky
Abstract: To investigate grain rotation caused by twinning-detwinning during plastic deformation, experiments using synchrotron high energy X-ray Diffraction (XRD) and Electron Backscatter Diffraction (EBSD) are carried out under in situ compression-tension loading. Comparison between the XRD and EBSD data confirms that the intensity change of diffraction rings in XRD experiment is caused by twining and detwinning. A good agreement of twin fraction values obtained from XRD and EBSD is achieved. This demonstrates that the grains and texture are homogeneously distributed along the normal direction of the sample. In the meantime, it is observed that detwinning can only be activated in a large quantity when the loading reverses into tension from compression in the first loading stage.
Authors: Seiji Miura, Hiroyuki Shimamura, Kenji Ohkubo, Tetsuo Mohri
Abstract: Investigation on the crystallographic orientation relationships among D022-Al3Ti, A15-Mo3Al and high temperature bcc phase consisting of an Al-Mo-Ti ternary alloy with an equi-axed two-phase structure was conducted by FESEM/EBSD analysis. The grains of intermetallic phases have certain crystallographic orientations each other, while the crystallographic orientation distributions become random after a high temperature deformation. This strongly suggests the grain boundary sliding and grain rotating govern the high temperature deformation, which is consistent with the fact that the strain-rate sensitivity m is 0.3 or higher during a steady-state compressive deformation.
Authors: H.P. Truong Qui, Horst Lippmann
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