Chemical Interaction of Constituent Atoms and Stability of Supercooled Liquid State in Zr-Based Metallic Glasses

Abstract

The chemical interaction (chemical bond) of constituent atoms in Zr₆₅Cu₃₅ and Zr₆₅Ni₃₅ metallic glasses has been investigated. The relationship between the stability of supercooled liquid state and the chemical bond is discussed. The feature of chemical bonds in those glasses was evaluated from the local electronic structures of hcp-like clusters which were calculated using the discrete-variational (DV)-Xα molecular orbital method. The hcp-like cluster models used here were constructed on the basis of local structure parameters determined by EXAFS (extended X-ray absorption fine structure) analysis. The strength of the Zr-Ni bond is larger than that of Zr-Cu bond, while the Cu-Cu bond strength is nearly equal to the Ni-Ni bond. Moreover, the strength of the Zr-Zr bond is larger in Zr₆₅Cu₃₅ glass than in Zr₆₅Ni₃₅ glass. This indicates that the formation of primary crystalline phase is more difficult in Zr₆₅Cu₃₅ glass than in Zr₆₅Ni₃₅ glass. The difficulty contributes to the relative stabilization of supercooled liquid state in Zr₆₅Cu₃₅ glass compared with that in Zr₆₅Ni₃₅ glass.