  We report on and characterize, via molecular dynamics (MD) studies, the
evolution of the structure of Cu50Zr50 and Cu64Zr36 metallic glasses (MGs) as
temperature is varied. Interestingly, a percolating icosahedral network appears
in the Cu64Zr36 system as it is supercooled. This leads us to introduce a
static length scale, which grows dramatically as this three dimensional system
approaches the glass transition. Amidst interpenetrating connections,
non-interpenetrating connections between icosahedra are shown to become
prevalent upon supercooling and to greatly enhance the connectivity of the MG's
icosahedral network. Additionally, we characterize the chemical compositions of
the icosahedral networks and their components. These findings demonstrate the
importance of non-interpenetrating connections for facilitating extensive
structural networks in Cu-Zr MGs, which in turn drive dynamical slowing in
these materials.
