  The mechanical properties of Mg-4wt.% Zn alloy single crystals along the
[0001] orientation were measured through micropillar compression at 23C and
100C. Basal slip was dominant in the solution treated alloy, while pyramidal
slip occurred in the precipitation hardened alloy. Pyramidal dislocations pass
the precipitates by forming Orowan loops, leading to homogeneous deformation
and to a strong hardening. The predictions of the yield stress based on the
Orowan model were in reasonable agreement with the experimental data. The
presence of rod-shape precipitates perpendicular to the basal plane leads to a
strong reduction in the plastic anisotropy of Mg.
