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Slip of low-angle tilt grain boundary (110) in FCC metals at perpendicular shear

Grain boundaries (GBs) make a significant contribution into the kinetics of plastic deformation of both polycrystalline and nanocrystalline metals. Among others, motion of GBs is an important phenomenon, which has to be taken into account in the consideration of the thermo-mechanical response of pol...

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Bibliographic Details
Published in:International journal of plasticity 2020-11, Vol.134, p.102843, Article 102843
Main Authors: Fomin, Eugeniy V., Mayer, Alexander E.
Format: Article
Language:English
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Summary:Grain boundaries (GBs) make a significant contribution into the kinetics of plastic deformation of both polycrystalline and nanocrystalline metals. Among others, motion of GBs is an important phenomenon, which has to be taken into account in the consideration of the thermo-mechanical response of poly- and nanocrystals. In this work, we study motion of low-angle tilt GBs and the accompanying relaxation of shear stresses in the case, when the shear is applied perpendicular to GB. Using the molecular dynamics (MD) simulations, we consider bicrystals made of aluminum, copper and nickel as FCC metals with different stacking fault energies. MD data are used for construction and verification of a GB motion model, which is based on the previously proposed equation of motion of a solitary dislocation in a single crystal. Within this model, a low-angle tilt GB is presented as a wall of periodically located perfect edge dislocations. The main driving factors are the external shear stress and the local stress distribution due to the plastic relaxation in the trace of each dislocation creating an area of partially relaxed stresses behind the shifted GB. These factors define the average GB velocity during the main stage of motion, while dislocation-dislocation interactions between the walls and inside each wall define details of the motion, such as the curvature of GBs and their mutual acceleration at the late stage of interaction of two approaching opposite GBs. [Display omitted] •Motion of low-angle grain boundaries (GB) in FCC metals is investigated by molecular dynamics.•GB moves as a wall of perfect dislocations, the corresponding model is constructed and verified.•Stress relaxation behind the dislocation wall considerably influences its motion.•Decrease in the stacking fault leads to splitting of GB dislocations on partial Shockley ones.•Variation of initial positions of dislocations can lead to instability of the dislocation wall.
ISSN:0749-6419
1879-2154
DOI:10.1016/j.ijplas.2020.102843