Nano icosahedral quasicrystals in Zr-based glassy alloys

A nanoscale icosahedral quasicrystalline phase formation was found by the slight deviation from the three-component rule for high glass-forming ability in a Zr65Al7.5Ni10Cu17.5 glassy alloy. Since the primary phase consists of fcc Zr2Ni and I-phases in the Zr65Al7.5Ni10Cu16.5(Ag, Pd, Au or Pt)1 glassy alloys, where an icosahedron is contained in both the phases, it is suggested that the local icosahedral atomic configuration exists in the glassy state and it stabilizes the supercooled liquid state. We also clarified that an I-phase precipitates in the Zr70Cu29Pd1 and Zr70Ni20Al9Pd1 glassy alloys and no I-phase formation is observed in the Zr70Ni29Pd1 amorphous alloy. Since the supercooled liquid region is confirmed in the Zr70Cu30 and Zr70Ni20Al10 glassy alloys and is not observed in the Zr70Ni30 amorphous alloy, it is concluded that the stability of the supercooled liquid state is strongly correlated with the existence of the local icosahedral order.