Al-Pd-Mn decagonal quasicrystals formed with different tiling structures

The formation of the decagonal quasicrystalline phase (D-phase) with about 1.2 nm periodicity in rapidly solidified and annealed Al70PdxMn30-x(x = 10-20) and Al100-2xPdxMnx (x=16-20) alloy ribbons was examined by X-ray diffraction and electron diffraction. The tiling structures of the equilibrium and non-equilibrium D-phases and the tiling changes resulting from the D-phase formation at different compositions have been revealed by high-resolution electron microscopy. The long-range quasiperiodic characteristics of the typical tiling structures have been compared in perpendicular space. An Al-Pd-Mn D-phase with a new kind of tiling structure (pentagonal tiling) was found in the Al68Pd16Mn16 ribbon annealed at 800 degrees C. The formation of the D-phases with different tiling structures is related to the different formation ratios for the basic structural units in the composition region for D-phase formation.