Small-angle neutron scattering study of amorphous isotopic Ni-Nb system

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

LOCAL ORDER IN Fe-B METALLIC GLASSES STUDIED BY HIGH-RESOLUTION NEUTRON DIFFRACTION

Le facteur de structure du système amorphe Fe-B, avec une concentration en bore allant de 14 à 25%, a été obtenu par diffraction des neutrons d'une source pulsée. Le domaine de vecteurs de diffusion exploré va jusqu'à 230 nm-1 ce qui permet d'atteindre une très bonne résolution. On en a déduit les distances entre proches voisins Fe-B et Fe-Fe, ainsi que la largeur de distribution de ces distances et les nombres de coordination. Les résultats sont interprétés sur la base d'un modèle de quasicristal.The structure factor of amorphous Fe-B system for 14-25 at% boron was measured by pulsed neutron diffraction up to 230 nm-1 resulting in high resolution in the distribution function. The first neighbour Fe-B and Fe-Fe distances, the width of their distributions and the coordination numbers are derived. The results are interpreted by quasi-crystalline model calculations