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Chemical short-range order in amorphous Ni-Ti alloys: an integral equation approach with a non-additive hard-sphere model

1989; IOP Publishing; Volume: 1; Issue: 22 Linguagem: Inglês

10.1088/0953-8984/1/22/008

1361-648X

Domenico Gazzillo, G. Pastore, Stefano Enzo,

Metallic Glasses and Amorphous Alloys

The authors analyse some of the most recent experimental scattering data for amorphous Ni-Ti alloys in terms of a non-additive hard-sphere (NAHS) model. The relevant correlation functions and structure factors are obtained by solving numerically the Ornstein-Zernike integral equations, supplemented by the Percus-Yevick closure, for Nix-Ti1-x systems with x=0.3, 0.4, 0.5 and 0.7. A comparison between additive and non-additive hard-sphere models is presented for x=0.5. Satisfactory semi-quantitative agreement with experimental data is then found for the Ni40Ti60 glass. The model is able to account for the appearance of a prepeak in the diffraction pattern as a natural consequence of the set-up of a chemical short-range order (CSRO) in the system. The usefulness of non-additive hard-sphere models for describing CSRO in metallic glasses is carefully discussed.