An intermediate state between the decagonal and monoclinic phases in an Al—Cu—Fe alloy

Abstract

An intermediate state between the decagonal quasicrystalline phase (D phase) and the monoclinic λ₂ phase has been discovered in an Al-Cu-Fe alloy. It is in fact a superstructure of the λ₂ phase with a double periodicity along the b axis, but it can also be treated as a phason-defected decagonal quasicrystal. In this state the quasiperiodic structure of the D phase has been transformed to being periodic along the plane perpendicular to the tenfold axis, and the periodicity along the tenfold axis remains unchanged.