The effect of solute segregation on strain localization in nanocrystalline thin films: Dislocation glide vs. grain-boundary mediated plasticity

Deformation mechanisms of nanocrystalline Au and AuCu thin films on compliant substrates were investigated by synchrotron-based in situ tensile testing and Automated Crystal Orientation Mapping using transmission electron microscopy. The results demonstrate that intragranular dislocation plasticity, inferred from evolution of deformation texture, is responsible for the formation of periodic and ordered shear bands in AuCu films. In contrast, pure Au films deform homogeneously without shear band formation and without evolution of deformation texture. Cu solutes are deemed to pin grain boundaries thereby enforce dislocation glide, while in pure Au, plasticity is carried by grain boundary shear and grain boundary migration.