Abstract
Nanostructured NiFe film was obtained on silicon with a thin gold
sublayer via pulsed electrodeposition and annealed at a temperature from
100 to 400 degrees C in order to study the effect of heat treatment on
the surface microstructure and mechanical properties. High-resolution
atomic force microscopy made it possible to trace stepwise evolving
microstructure under the influence of heat treatment. It was found that
NiFe film grains undergo coalescence twice-at similar to 100 and similar
to 300 degrees C-in the process of a gradual increase in grain size. The
mechanical properties of the Au/NiFe nanostructured system have been
investigated by nanoindentation at two various indentation depths, 10
and 50 nm. The results showed the opposite effect of heat treatment on
the mechanical properties in the near-surface layer and in the material
volume. Surface homogenization in combination with oxidation activation
leads to abnormal strengthening and hardening-up of the near-surface
layer. At the same time, a nonlinear decrease in hardness and Young's
modulus with increasing temperature of heat treatment characterizes the
internal volume of nanostructured NiFe. An explanation of this
phenomenon was found in the complex effect of changing the ratio of
grain volume/grain boundaries and increasing the concentration of
thermally activated diffuse gold atoms from the sublayer to the NiFe
film.
Users
Please
log in to take part in the discussion (add own reviews or comments).