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.