A study of amorphous alloys of Au with group III A elements (Y and La) formed by a solid-state diffusion reaction

Amorphous alloys AuXM1-x, with x ≅ 0.5, where M is La or Y, have been formed through solid-state interdiffusion reaction of pure polycrystalline Au, La, and Y thin films (200 to 600 Å thickness) at temperatures of 50-130 C. For x ≳ 0.7 the end product of the reaction is a two phase material containing polycrystalline Au and amorphous AuM, while for x ≲ 0.3 the end product is amorphous AuM plus polycrystalline M. The attainment of these products is explained in terms of the common tangent rule applied to the Gibbs free energy diagram of the amorphous alloy and the crystalline compounds observed. © 1984.