Structural origin of the high glass-forming ability of Ce70Ga10Cu20 alloys

Abstract

The CeGaCu amorphous alloy has a good glass-forming ability and many special properties. However, its structure at the atomic scale is unclear. We systematically investigated the structure evolution of Ce₇₀Ga_xCu_30−x (x = 6, 10, 13) glass formation melts by ab initio molecular dynamics (AIMD) simulations. Based on the trajectories from the simulations, the pair-correlation function, coordination numbers, chemical short-range order, Voronoi polyhedra and electronic structures were discussed. Our results show that the concentration of Ga- and Cu-centered icosahedral (-like) clusters in Ce₇₀Ga₁₀Cu₂₀ melts are larger than those in Ce₇₀Ga₆Cu₂₄ and Ce₇₀Ga₁₃Cu₁₇ melts. Furthermore, electronic analysis showed that the hybridization between Ga 4p and Cu 3d (Ce 5d) orbitals is strong and that of Cu 3d orbitals and Ga 4p orbitals was strengthened in Ce₇₀Ga₁₀Cu₂₀ melts, which means that the interactions between Ga and Cu atoms nearby were enhanced in the Ce₇₀Ga₁₀Cu₂₀ melts. The stability of the Ga- or Cu-centered icosahedral clusters increased accordingly, which favored their glass-forming ability. Our investigation helps people obtain an increased understanding of the glass-forming ability from the viewpoint of chemical interactions for metallic glasses.