Formation of Millimeter-Sized Al–Cu–Ru Single Quasicrystals

Millimeter-sized Al–Cu–Ru single quasicrystals in a shape of a pentagonal dodecahedron were produced by slow cooling from just above the melting point. The alloy ingot was held at 1323 K for 2 h. Then it was slowly cooled to 1123 K in 33.3 h and subsequently cooled to room temperature in a furnace. Single quasicrystals were obtained in three compositions, Al61.6Cu24.8Ru13.6, Al68.1Cu16.1Ru15.8 and Al58.3Cu27.9Ru13.8. The compositions of three single quasicrystals fall nearly on a e⁄a=1.75 straight line. An X-ray Laue pattern corresponding to the five-fold symmetry shows a clear petal-like pattern. The X-ray diffraction profiles were measured using a four-circle diffractometer for the Al–Cu–Ru alloys. There is no qualitative difference between Al61.6Cu24.8Ru13.6 and Al68.1Cu16.1Ru15.8.