A study of the high-Cu Al–Cu–Co decagonal phase

Abstract

The decagonal phase was studied by transmission and scanning electron microscopy in an Al₆₂Cu₂₄Co₁₄ alloy annealed at 550–850 °C. The electron diffraction patterns of the decagonal phase exhibited weak quasiperiodic odd-n reflections in the [1-2100] zone axis corresponding to the equilibrated structure. The relative intensities of these reflections were significantly lower in the Al₆₂Cu₂₄Co₁₄ than in the Al₆₈Cu₁₁Co₂₁ decagonal phase. Diffuse scattering observed previously at the same positions can be related to a nonequilibrium state of the decagonal phase.