Local structures and structural phase change in Ni-Zr-Nb glassy alloys composed of Ni₅Zr₅Nb₃ icosahedral clusters

We construct a local structural model for Ni-Zr-Nb glassy alloys, Ni ₄₈Zr₄₀Nb₂₄, which contains eight icosahedra of Ni₅Zr₅Nb₃ as the structural units. We fully optimize the 112-atom structures by first principles calculation, and find two characteristic phases in the structures depending on the alignment of the icosahedra: an amorphous phase where the icosahedral structure well remains and a periodic phase corresponding to crystallization where the icosahedra change to fcc-like cuboctahedra. Nb atom-clustering may play a key role in anti-crystallization.