Ordered clusters and free volume in a Zr-Ni metallic glass

The atomic arrangement of a model metallic glass Zr2Ni was studied by extended x-ray absorption fine structure and x-ray scattering experiments combined with reverse Monte Carlo simulation imposed an additional potential constraint. By an approach to calculating the free volume (FV) on atomic level, we have found a connection between the coordination number and FV, and then revealed that the atomic structure of Zr2Ni metallic glass is essentially an association of the ordered clusters and FV. The ordered clusters about 1.5 nm consist of a densely packed core (i.e., icosahedral or fcc-type packing) and the surrounding loosely packed clusters with large FV. (C) 2008 American Institute of Physics.