Study of medium range ordering for metal-metalloid glasses near crystallization temperature

Unlike crystalline materials characterized by long range ordering, amorphous materials show short and middle range ordering. The atomic arrangements in multi-component metallic/metal-metalloid glasses remain a challenging problem, especially their structure near crystallization point have not been reported. In a popular model for amorphous materials, the structure is characterized by two parameters: the fractal dimension (which represents the density of atoms in self-similar clusters) and cut-off length (which represents the length scale up to which the atom-atom correlations are significant). From analysis of synchrotron X-Ray diffraction data for as cast as well as vacuum annealed metal-metalloid glasses with composition Fe58Co25Nb7Cu1B9, we find that the fractal dimension increases from 2.24 for the as cast sample to 2.45 for partially crystallized sample annealed at 450°C. The cut-off lengths remain the same within error. Further, we find that the power law scaling proposed for as cast metallic glasses by Ma et al as q1.Va-1/df = 9.3 may be adequate for describing structure of metal-metalloid amorphous systems near crystallization.