Structure of liquid alloys of the Au-Si and Au-Ge systems

Abstract

A study of the liquid alloys of the simple eutectic systems Au-Si and Au-Ge at selected compositions has demonstrated a pattern of behaviour very similar to that seen in the related gold-based system Au-Sn. The sharp X-ray diffraction profile of Au-Ge liquid alloys at the gold-rich end demonstrates that the structure, like that of pure Au, is simple, close-packed but with a mean closet distance for neighbouring atoms smaller than that for liquid Au or Ge. This result is also obtained for liquid Au-Si alloys. The packing in the liquid phase can only be interpreted in terms of A-B bonding, i.e. unlike atom interaction, a feature attributed to a high electrochemical factor. With higher Ge content, the X-ray diffraction profile broadens in a manner consistent with a more open liquid structure. The author accounts for the latter in terms of the increasing influence of Ge-Ge nearest neighbour packing.