  When Chen et al. (2015, Acta Mater. 87, 78-85) investigated the deformation
behavior of oligocrystalline gold microwires with varying diameters in both
uniaxial tension and torsion, contrary size effects were observed for the
different load cases. In accompanying microstructural studies it was found,
that the microwires of different thickness reveal distinctive differences in
grain size and texture, respectively. As a consequence, a significant influence
of these microstructural variations on the determined size effects was assumed.
However, within the frame of their work, a direct confirmation could only be
presented for the effect of the grain size. In the present work, the
size-dependent mechanical response of the microwires is modeled with a gradient
plasticity theory. By finite element simulations of simplified grain
aggregates, the influence of the texture on the size effects is investigated
under both loading conditions. It is shown that the experimentally observed
contrary size effects can only be reproduced when taking into account the
individual textures of the microwires of different thickness within the
modeling.
