Stable decagonal quasicrystals with a periodicity of 1·6 nm in Al-Pd-(Fe, Ru or Os) alloys

A decagonal (D) phase with a periodicity of 1·6 nm along the periodic axis (c-axis) was found in Al-Pd-Fe alloys in the melt-quenched state as well as the annealed state after conventional solidification. The D-structure is stable even after being annealed at 1110 K for 48 h. The stable D-phase was also found in Al-Pd-Ru and Al-Pd-Os alloys. In contrast with D-AlPd, one of the twofold diffraction patterns (P-pattern (see text)) shows a different extinction rule, indicating that D-AlPdFe has a novel structure with a different chemical ordering which is presumed to arise between Fe/Al or Fe/Pd.