Structure Factors of Binary Aluminum-Nickel and Ternary Aluminum-Nickel-Silicon Liquid Alloys

Abstract

Abstract A calculation of the structure of binary Al—Ni and of ternary Al—Ni—Si alloys based on a multicomponent hard sphere model and a square well like interatomic potential is developed in connection with chemical short range order in these alloys. Maret et al. 1 using the isotopic substitution method, measured the partial structure factors of the binary Al80Ni20 alloy. They obtained a prepeak in the partial Ni—Ni structure factor and a preminimum in the Ni—Al partial structure factor. We obtain the same features with a square well potential, but not with hard spheres. It has been shown by Chenal2 that liquid ternary alloys at an amorphisable composition such as Al65Ni15Si20 present a prepeak in the total structure factor, which is absent at a slightly different compostion of Ni: Al75Ni5Si20. We show here that ternary hard sphere structure factors with additive hard spheres cannot explain any prepeak, while such a feature can be reproduced from square well attractions but only at the right composition.