Growth mode of decagonal quasicrystal phase in laser resolidified Al72Ni12Co16 alloy

The ultra-high-temperature gradient directional solidification process prod uced by laser beam was adopted to achieve the directionally solidified micr ostructure and analyze the growth pattern of the stable decagonal quasicrys tal phase in Al72Ni12Co16 alloy. The X-ray, SEM, TEM and optical microscopy techniques were used to investigate the microstructures and identify the p hase. The directionally solidified decagonal quasicrystal showed the facet morphology and grew in lateral growth mode. The unusual periodic and quasip eriodic atomic structures of the decagonal quasicrystal and the epitaxial g rowth in the melt pool were considered to be the key factors influencing th e growth morphology. The experimental results were well explained by the To ner's theoretical atomistic growth model. (C) 1999 Elsevier Science B.V. Al l rights reserved.