Response of the Al Sigma 5 < 001 > 310 Symmetric Tilt Grain Boundary to the Shear Deformation Simulated by Molecular Dynamics
KY Cheng and C Lu and K Tieu, SCIENCE OF ADVANCED MATERIALS, 6, 1322-1329 (2014).
In the present study, shear response of the Al 001 symmetrical tilting Sigma 5 (310) grain boundary (GB) was investigated by a three dimensional bicrystal at 500 similar to 750 K. It was found that the GB gradually rotated around the 001 tilt axis during the shear deformation due to the combination of surface strain, GB sliding and GB coupled motion. These rotated grain boundaries were Sigma 5 asymmetrical or symmetrical tilt grain boundaries and led to the normal stress sigma(xx) in the bicrystal system. It was also found that the response of the grain boundary to the shear deformation was closely related to the temperatures. At lower temperature (500 similar to 650 K), further shear deformation was mediated by crack initiation or dislocation release which is closely related to the local stress condition and temperature etc. The lattice dislocations emitted from GB were identified as pure edge dislocations with Burgers vectors of < 110 >/2. Interestingly, they have the 001 line direction and glide on the 110 planes. The reaction between grain boundary and lattice dislocations has been carefully discussed with its role in the shear deformation. At higher temperatures (above 700 K), after a short while of perfect coupling at the early stage the grain boundary quickly rotated and the two grains smoothly slid away from each other in the way of viscous grain boundary sliding under the shear deformation.
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