The growth of decagonal quasicrystals was investigated by the directional solidification of highly undercooled Al72Ni12Co16 melts. The maximum single-grain decagonal quasicrystal contained in the grown crystals was about 0.5 mm in diameter and 6 mm in length. The quality of the grown crystals was examined by the X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). (c) 2005 Springer Science + Business Media, Inc.