STRUCTURE OF AMORPHOUS NI-PD-P AND FE-PD-P ALLOYS

Ternary alloys of nickel-palladium-phosphorus and iron-palladium-phosphorus containing 15-20 at.% phosphorus were rapidly quenched from the liquid state. The structures of the quenched alloys were investigated by x-ray diffraction. Broad maxima in the diffraction patterns, indicative of a glass-like structure, were obtained for 13-73 at.% nickel and 13-44 at.% iron, with palladium and phosphorus adding up to 100%. The interference functions were evaluated from the coherent x-ray scattering and used to compute the electronic radial distribution functions for these alloys. Average interatomic distances and coordination numbers were obtained from the radial distribution functions. A linear relationship between interatomic distances and composition, similar to Vegard's law in crystalline systems, was shown for these metallic glasses. The structure of the quenched Ni-Pd-P and Fe-Pd-P alloys could be explained in terms of structural units analogous to those existing in the metal-rich phosphides. A quasi-crystalline model based on the Pd3P structure, with nickel or iron substituting for palladium, was shown to give a very satisfactory approximation of the amorphous structure of the Ni-Pd-P and Fe-Pd-P alloys. Such a model was also in good agreement with electrical and magnetic properties measured for these metallic glasses. © 1969 The American Institute of Physics.