A new hexagonal phase displaying pseudo-icosahedral symmetry in Zn–Mg–Y alloy

  A number of hexagonal phases displaying pseudo-icosahedral symmetry have been reported in Zn–Mg–RE alloy, but no cubic or orthorhombic approximants. In the present work another new hexagonal phase, H′ (a = 9.1 Å, c = 19.7 Å), was found to coexist with H-(Zn,Mg)5Y. Their orientation relationship was determined to be 〈1 0 0〉H′ || 〈1 0 0〉H, [0 0 1]H′ || [0 0 1]H. Since their electron diffraction patterns are similar to the corresponding patterns of an icosahedral quasicrystal, they are both considered to be approximants of the Zn–Mg–Y icosahedral quasicrystal.