Growth of decagonal quasicrystal phase in laser resolidified Al72Ni12Co16

Growth of decagonal quasicrystal phase in laser resolidified Al72Ni12Co16

An ultra-high temperature gradient directional solidification process produced by a widened laser beam was adopted to achieve the directionally solidified microstructure of the stable decagonal quasicrystal phase in Al₇₂Ni₁₂Co₁₆ alloy. X-ray, SEM, TEM and optical microscopy techniques were used to investigate the microstructures and identify the phase. The directionally solidified decagonal quasicrystal showed the facet morphology and grew in lateral growth mode. The unusual periodic and quasiperiodic atomic structures of the decagonal quasicrystal and the epitaxial growth in the melt pool were considered to be the key factors influencing the growth morphology. The experimental results were consistent with the Toner’s theoretical atomistic growth model.