This work focuses on the anisotropic deformation and fracture mechanisms of a typical
physical vapor deposited TiN/ZrN multilayer, employing novel nanoindentation and micropillar
compression techniques. The results highlight a stronger nanoindentation response
of the multilayer when loaded perpendicular (90 degrees) to the layer orientation,
and the deformation was mainly controlled by the plasticity of ZrN layers. In comparison,
at parallel (0 degrees) orientation, the kink banding and the induced cracking may
weaken the constraint beneath the indenter, thus leading to degraded hardness. By
considering the anisotropic deformation mechanisms, nanoindentation finite element
modeling was further performed to give reliable predictions on the strength at the
inclined orientation. The modeling results suggest a dominant deformation mechanism
that occurred mainly in the ZrN layers, with minor contribution from the stiff TiN
layers. As a result, a minimized hardness was predicted at 45 degrees loading direction
with respect to layer orientation. Finally, the micropillar compressions show a brittle
nature of both 90 degrees and 0 degrees oriented micropillars, and a higher fracture
strain was obtained at 90 degrees, due to the observed crack termination mechanism
at this orientation.
