Partial structure factors and chemical short-range order in Ni₃₃Y₆₇and Cu₃₃Y₆₇metallic glasses

Abstract

The three Faber-Ziman partial structure factors as well as the Bhatia-Thornton (1970) structure factors of the Ni33Y67 and Cu33Y67 metallic glasses have been evaluated by neutron diffraction using the isotopic substitution method and X-ray diffraction. The chemical ordering is described by a function alpha (R) related to the partial coordination numbers zij(R). The relevant CSRO parameter alpha 1 in the first coordination shell is chosen equal to the value of alpha (R) at the position of the first minimum of GNN(R). Thus, the parameters alpha 1 show a strong chemical ordering in Ni33Y67 and, in contrast, a tendency towards random mixing of both constituents in Cu33Y67. The evaluation of alpha 1 by the same method in several NixMt1-x glasses (x approximately=0.33, Mt=Y, Ti, Zr, Dy) gives evidence of a relation between the strength of the bonding and the nature of the d transition element alloyed with Ni.