Exploration of the icosahedral clusters in Ni–Nb binary metallic glasses via first-principles theory

Abstract

The binding energy, chemical ordering parameters, and electronic structure of Ni-centered NinNb13−n(n = 6, 7, 8, 9) icosahedral clusters were studied in accordance with the first-principles theory. These calculations demonstrated that the binding energy of the icosahedral clusters decreased when the homogeneous shell atoms preferred to bond together. The density of state at the EF of most icosahedral clusters was near a gap, indicating that all icosahedral clusters were in a relatively stable state. For the icosahedral cluster, the states near the Fermi level were dominated by Ni- and Nb-d electrons. The electron-localization function analysis of the most stable and unstable structures in icosahedral clusters showed that chemical bonding favored the formation of icosahedral clusters by introducing a string-like or net-like structure and further stabilized icosahedral clusters. The origin of glass-forming ability (GFA) was the synergistic effect of electronic stability and topological stability of icosahedral clusters in Ni–Nb metallic glasses.