Atomic structure of Co92−xBxTa8 glassy alloys studied by ab initio molecular dynamics simulations

Abstract

AbstractThe ab initio molecular dynamics simulations were adopted to study the atomic structures of Co92−xBxTa8 (x = 30, 32.5, 35, 37.5, at%) glassy alloys. The results showed that the local packing of B‐centered clusters was more efficient than that of Co‐ and Ta‐centered clusters. It was also found that B‐centered clusters were the primary structure‐forming clusters. The Kasper polyhedra with a Voronoi index of <0 3 6 0> and <0 2 8 0> are dominant in B‐centered clusters. The <0 3 6 0> clusters could especially be formed into a robust network structure, which plays a key role in the increase of mechanical properties. Such a network structure has a higher activation barrier for structural rearrangement and a larger resistance to plastic flow. Thus, the increase in the fraction of <0 3 6 0> with B content would result in an increase in yield strength, as well as a sharp decrease in compressive plasticity.