Metallic glasses have been studied vigorously since the
first report on amorphous gold-silicon alloy back in 1960.[1]
Initially soft magnetic properties were the most promising
features for industrial applications. The recent development
of bulk metallic glasses (BMGs)[2–5] initiated interests in engineering
applications such as structural or biomedical materials
because of attractive properties such as high strength,[6]
high elasticity,[7,8] and good corrosion resistance,[9,10] among
others. In addition, high temperature processing of BMGs
allows for near-net-shape formability,[11–13] which could simplify
and possibly reduce the cost of the final product.
The glasses retain the disordered atomic structure of a liquid,
and ideally are isotropic solids. Frequently because of
processing conditions, such as directional heat flow, some
structural anisotropy is produced during quenching, and has
been observed by structural investigations. Usually, annealing
at high temperatures results in an isotropic structure.
Also, formation of uniaxial magnetic anisotropy[14] had been
observed in studies of creep deformed ferromagnetic metallic
glasses. Samples with a near-zero magnetostriction coefficient
had been studied to establish the origin of the magnetic
anisotropy. It was concluded that anisotropy resulted from
the atomic level anisotropy[15] and not the heterogeneous internal
stress distribution. Indeed X-ray diffraction study of
the creep deformed metallic glass showed bond anisotropy.[
16,17] Such structural studies had been cumbersome and
lengthy because they required measurement of many orientations
with high statistics. Recently we have shown that use of
an area detector and high energy X-rays at a synchrotron
source can speed up data collection without compromising
statistics.[18] In this contribution, we present data showing
structural anisotropy in glassy samples after homogenous
(creep) and inhomogeneous (compression) mechanical deformation.
The observation of the structural anisotropy after
mechanical deformation can provide insight into the atomistic
mechanism of the deformation process in metallic glasses.