Thermal stability of decagonal quasicrystal prepared from undercooled Al72Ni12Co16 alloy melt

The thermal stability of the single-phase decagonal quasicrystal produced directly from the undercooled Al72Ni12Co16 alloy melt was investigated by different heat treatments. The optical microscopy, TEM, X-ray powder diffractometer (XRD) and differential thermal analyzer (DTA) techniques were adopted to observe the microstructure and to characterize the phase composition, respectively. Based on the analyses of the X-ray diffraction patterns and the DTA curves, two modifications of the decagonal quasicrystal existed in the annealed samples, which have a close structural relationship to the decagonal quasicrystal.