FORMATION OF MILLIMETER-SIZED AL-CU-RU SINGLE QUASI-CRYSTALS

Millimeter-sized Al-Cu-Ru single quasicrystals in a shape of a pentago nal dodecahedran mere produced by slow cooling from just above the mel ting point. The alloy ingot was herd at 1323 K for 2 h. Then it was sl owly cooled to 1123 K in 33.3 h and subsequently cooled to room temper ature in a furnace. Single quasicrystals were obtained in three compos itions, 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 Lane pattern corresponding to the five-f old symmetry shows a clear petal-like pattern. The X-ray diffraction p rofiles were measured using a four-circle diffractometer for the Al-Cu -Ru alloys. There is no qualitative difference between Al61.6Cu24.8Ru1 3.6 and Al68.1Cu16.1Ru15.8.