A New Series of Icosahedral Quasicrystals in Zn-M-Sc (M = Ag, Au, Pd, Pt) Alloys

A new series of icosahedral quasicrystals has been found in Zn 75 M 10 Sc 15 (M = Ag, Au, Pd and Pt) as-cast alloys. Electron and powder X-ray diffraction analyses indicated that these quasicrystals are of the P-type (primitive type) and have six-dimensional lattice parameters a 6D =0.7112–0.7151 nm. The quasicrystals are formed as main phases in these alloys. In the Zn 80 Ag 5 Sc 15 alloy annealed at 981 K for 24 h, a Zn 85 Sc 15 -type cubic phase is formed exclusively, which has the lattice parameter a =1.3867 nm. The cubic phase is interpreted as a 1/1 approximant of Zn 75 Ag 10 Sc 15 . This observation, as well as intensity similarity in the X-ray diffraction patterns, suggests that Zn 75 M 10 Sc 15 quasicrystals belong to the same group as the Zn 80 Mg 5 Sc 15 quasicrystal from the viewpoint of a local atomic configuration.