Ab-Initio Data for Interatomic Interactions in Zr-Rich Z_rX (X velence Sc-Cu) Alloys and Stability of Icosahedron-Like Zr_(13-n)Cu_n (n velence 3, 4) Clusters in Zr_70Cu_(30) Metallic Glass

摘要

We give ab-initio data for the study of the stability of the atomic structures of Zr-rich Z_rX (X velence Sc-Cu) alloys, such as the cohesive energies and equilibrium Wigner-Seitz radii of elemental metals X (X velence Sc-Cu, Zr-Ag) and X-X (X velence Sc-Cu) interaction energies in Zr. The calculations are based on the density functional thoery in the generalized gradient approximation and employ the full-potential Korringa-Kohn-Rostoker Green's function method. Using the calculated results, we elucidate the fundamental features of interatomic interactions of Zr-rich Z_rX alloys. Especially, we found that the pair interaction of Cu impurities in Zr becomes strongly attractive around the interatomic distance of 0.45 approx 0.46nm. It is shown that this interaction may be important for the stability of icosahedron-like local atomic structures of Zr_10Cu_3 and Zr_9Cu_4 clusters in the Zr_(70)Cu_(30) bulk metallic glass, being proposed experimentally. We also found that the atomic structure of an isolated Zr_(10)X_3 cluster transforms from the hcp structure (initial state) to an icosahedron-like structure (final state) for X velence Cu, but not for X velence Ni.