Comparative study of local atomic structures in Zr2CuxNi1-x (x=0, 0.5, 1) metallic glasses

Extensive analysis has been performed to understand the key structural motifs accounting for the difference in glass forming ability in the Zr-Cu and Zr-Ni binary alloy systems. Here, the reliable atomic structure models of Zr2CuxNi1-x (x = 0, 0.5, 1) are constructed using the combination of X-ray diffraction experiments, ab initio molecular dynamics simulations and a constrained reverse Monte Carlo method. We observe a systematic variation of the interatomic distance of different atomic pairs with respect to the alloy composition. The ideal icosahedral content in all samples is limited, despite the high content of five-fold symmetry motifs. We also demonstrate that the population of Z-clusters in Zr2Cu glass is much higher than that in the Zr2Ni and Zr2Cu0.5Ni0.5 samples. And Z12 < 0, 0, 12, 0 > Voronoi polyhedra clusters prefer to form around Cu atoms, while Ni-centered clusters are more like Z11 < 0, 2, 8, 1 > clusters, which is less energetically stable compared to Z12 clusters. These two different structural properties may account for the higher glass forming ability of Zr2Cu alloy than that of Zr2Ni alloy. (C) 2015 AIP Publishing LLC.