Abstract:The potential energies, volumes and electronic structures of characteristic atoms coordinated by neighboring configurations were obtained from the experimental heats of formation and lattice parameters of disordered Au_1−xCu_x alloys. From characteristic atom occupation (CAO) patterns of L1₂-Au₃Cu, L1₂-AuCu₃ and L1₀-AuCu compounds, their electronic structures, volumetric and energetic properties were calculated. The CAO pattern of Johasson−Linde(J−L) model shows that the transition AuCuI→AuCuII is an exothermic and volume contraction reaction, which is opposite from experimental phenomena. According to CAO pattern of Guymont−Feutelais−Legendre(G−F−L) model, the AuCuII cell consists of two periodic antidirection (PAD) AuCuI regions and two PAD boundary regions. The equations derived from CAO pattern of G−F−L model can be used to calculate energetic properties, volumetric properties and ordering degrees of the PAD AuCuI region and PAD boundary region, as well as corresponding average properties of the AuCuII phase. The results are consistent with experimental phenomena.

Key words: Au-Cu system; intermetallics; electronic structure; crystalline structure; characteristic atom occupation pattern