The structures and phase transformations in β-AuCd alloys

An X-ray powder diffraction and single-crystal study of the structures and phase transformations existing in the 50 at.% region of the gold-cadmium system has been carried out. The transformation β₁ (cubic) →β′ (orthorhombic) occurring in the range 47–48.5 at.% Cd is confirmed. At higher cadmium content, 49–52 at.%, the cubic β₁ phase transforms to a structure possessing hexagonal symmetry rather than the previously suggested tetragonal structure. The X-ray diffraction patterns of this hexagonal structure can be interpreted in terms of a unit cell of 27 atoms, which is structurally similar to the ξ phase of the AgZn system.