Evidence for a new Hume-Rothery phase with an amorphous structure

Abstract

It will be shown that binary amorphous alloys with a noble metal and a polyvalent non-transition element, as constituents, can be described essentially as a Hume-Rothery phase. Some structural as well as transport properties depend on\(\bar Z\), the average number of the conduction electrons per atom. A strong similarity between the amorphous and the corresponding liquid alloys was found. Alloys of the type mentioned can exist in a homogeneous amorphous phase within a concentration range which is limited on the noble-metal rich side by\(\bar Z\)=1.8 and on the other side by about 20 at% noble-metal content. The influence of the conduction electrons, manifested in the Friedel oscillations of the effective pair potentials, is responsible for structural and electronic transport properties. For amorphous and liquid alloys with\(\bar Z\)=1.8 it is interesting to note thatkpe, the wave number at which the maximum in the structure factor occurs, is equal to 2kF, the diameter of the Fermi sphere. As far as we have determined, all amorphous alloys with\(\bar Z\)=1.8 containing the same noble metal have the same crystallization temperature and the same Hall coefficient independent of the polyvalent element. The individual influence of the polyvalent constituents can only be seen with increasing\(\bar Z\).