Peculiarities of plasticity nucleation in alpha-iron nanowires

The peculiarities of the nucleation and propagation of structural defects in iron nanowires with an ideal bcc lattice under uniaxial tension along various crystallographic directions were studied. The study was carried out in the framework of the molecular dynamics method. It was found that the mechanisms of nucleation of plastic deformation substantially depend on the orientation of the nanowire with respect to the direction of loading. Reaching the elastic limit at stretching along the direction leads to the generation of a twin on one of the sample edges. Dislocations are nucleated only in the twin body. Local regions with an fcc lattice can form in the vicinity of twinning dislocations. A large number of twins with a high growth rate and small thickness is formed in the sample at tension along the direction. During the loading, these twins tend to transform into screw dislocations. The nucleation of plastic deformation has an clearly defined dislocation nature in the case of stretching of the sample along the [111] direction. During loading, the number of dislocations increases in an avalanche-like manner, then the dislocations escape to free surfaces, leaving vacancies in the bulk of the sample at the intersection points.

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