Radial distribution function of amorphous Ni [sbnd]Pt [sbnd]P alloys

Abstract

Accurate X-ray diffraction measurements were made upon five amorphous alloys having the composition (Ni x Pt 100− x ) 75 P 25 with 20 ⩽ x ⩽ 60, which were obtained by rapid quenching from the liquid state. The shapes of the interference function a( K), and of the atomic radial distribution function (RDF) curves are strikingly similar to those observed for metallic liquids. Contrary to what was observed in previously studied amorphous metallic alloys, there is no shoulder on the high angle side of the second peak of a( K) and the RDF does not have a double peak beyond the first maximum. The ratio of second to first near-neighbor atomic distances is 1.86±0.02, a value which is larger than that (∼1.7) observed for previously known amorphous foils. The first coordination number is close to 12. On the basis of these and further experimental studies on the first band of various amorphous metallic alloys, it is concluded that the present alloys possess a higher degree of disorder than that found in any of the existing amorphous metallic materials. The degree of disorder is comparable to that present in fused silica. The factors contributing towards successful synthesis of these alloys are discussed.