Dynamic behavior of atomic clusters during structural relaxation in metallic glasses

To understand the relationship between static structures, characterized by the well-known Voronoi polyhedra, and the structural relaxation process of metallic glasses, the structural changes associated with different atomic clusters during isothermal processes at 300 and 900 K in Zr₈₀Pt₂₀ are investigated using molecular dynamics simulations. These two temperatures are characterized by plateau and slope regions in the self-intermediate scattering function profiles. Atomic clusters are tracked based on their Voronoi polyhedra, and the fraction of atomic clusters that maintain their original structure during the relaxation processes is calculated to determine their structural persistence. Particularly at 300 K, the structural persistence of each atomic cluster follows a power law when the caging effect is strong, despite the total fraction of each atomic cluster being largely unchanged. Moreover, the structural persistence of the major atomic clusters is closely related to the number of pentagonal faces in the Voronoi polyhedra.