Étude par diffraction de rayons X d'alliages or-cuivre de composition intermédiaire entre celles des alliages de type AuCu₃ et de type AuCu (teneur en or comprise entre 35 et 37 at.%)

A narrow two-phase region (of composition width about 1 at. %) separates alloys of types AuCu and AuCu₃ in the neighbourhood of the composition Au₃₆Cu₆₄. A tetragonal deformation of the unit cell is observed as much in the ordered AuCu₃ I structure as in the periodic antiphase structure, AuCu II, the deformation being due to preferential occupation of certain sites by gold atoms. Two one-dimensional periodic antiphase structures of the type AuCu₃ II are observed, with one antiphase direction parallel to a, AuCu₃ II'-a, the other parallel to c, AuCu₃ II'-c. The symmetry of the elementary cell of AuCu₃ II'-a would appear to be not tetragonal but orthorhombic.