Nucleation of dislocations from 001 bicrystal interfaces in aluminum

D. E. Spearot, K. I. Jacob, D. L. McDowell, Acta Materiala 53, 3579-3589 (2005).

It is well established from molecular dynamics simulations that grain boundaries in nanocrystalline samples serve as sources of dislocations. In this work, we use molecular dynamics simulations to study the mechanisms associated with dislocation nucleation from bicrystal 001 interfaces in aluminum. Three interface misorientations are studied, including the R5 (310) boundary, which has a high density of coincident atomic sites. Molecular dynamics simulations show that full dislocation loops are nucleated from each interface during uniaxial tension. After the second partial dislocation is emitted, a ledge remains within the interface at the intersection of the slip plane and the bicrystal boundary. A disclination dipole model is proposed for the structure of the distorted interface accounting for local lattice rotations and the ledge at the nucleation site.

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