Anisotropic Size-Dependent Plasticity in Face-Centered Cubic Micropillars Under Torsion

Three-dimensional dislocation dynamics (DD) simulations are performed to investigate the size-dependent plasticity in submicron face-centered cubic (FCC) micropillars under torsion. By using a previously implemented surface nucleation algorithm within DD, we show that the plastic behavior of FCC micropillars under torsion is strongly affected by the crystallographic orientation: In < 110 > oriented submicron pillars, coaxial dislocations nucleate and pile up near the axis, leading to homogeneous deformation along the pillars. In contrast, in < 100 > and < 111 > oriented pillars, heterogeneous plasticity has been observed due to the formation of localized dislocation arrays. As a result of the existence of a coaxial slip plane in < 110 > oriented pillars, stronger size-dependent plasticity is observed in this case compared with those in other orientations.