Orientation-Dependent Plasticity in Metal Nanowires under Torsion: Twist Boundary Formation and Eshelby Twist

We show that the plastic deformation of nanowires under torsion can be either homogeneous or heterogeneous, regardless of size, depending on the wire orientation. Homogeneous deformation occurs when < 110 >-oriented face-centered-cubic metal wires are twisted, leading to the nucleation of coaxial dislocations, analogous to the Eshelby twist mechanism. Heterogeneous deformation is predicted for < 111 > and < 100 > wires under torsion, localized at the twist boundaries. These simulations also reveal the detailed mechanisms of twist boundary formation from dislocation reactions.