SMALL-ANGLE NEUTRON-SCATTERING STUDY OF AMORPHOUS ISOTOPIC NI-NB SYSTEM

Inhomogeneities in amorphous Ni-Nb samples prepared from various Ni-is otopes are investigated for two compositions, Ni-44 at% and Ni-62 at% by small-angle neutron scattering (SANS) in the scattering vector rang e from 0.007 to 0.45 angstrom-1. A strong increase in the structure fa ctors is observed below 0.04 angstrom-1 whereas above 0.06 angstrom-1 they smoothly become constant. In order to clarify the origin of SANS the total structure factors are separated into the Bhatia-Thornton par tial structure functions. It is shown that, the inhomogeneities are bo th topological and chemical in character. A characteristic correlation length of about 180 angstrom is obtained.