Abstract
A new Al-Mn orthorhombic crystalline phase isostructural with Al60 Mn11 Ni4, Al20 Mn3 Cu2, and the T3 AlMnZn phase has been found in coexistence with the decagonal quasicrystal in a rapidly solidified Al-Mn alloy. From the structure of this Penrose-tiling approximant two sets of Penrose-type tiles were derived. A structural model of the Al-Mn decagonal quasicrystal based on these tiles was proposed. This model agrees well with the recent experimental X-ray structural determination of the Al-Mn decagonal quasicrystal.