A new highly ordered Al-Ni-Ru decagonal quasicrystal with 1.6 nm periodicity

A new decagonal quasicrystal (the D phase) with a period of about 1.6 nm wa s found to Form in conventionally solidified and heat-treated Al75Ni15Ru10 alloys. The electron diffraction patterns of the Al-Ni-Ru D phase exhibit a large number of quite sharp diffraction spots located at precise decagonal symmetry positions, indicating a highly ordered decagonal quasicrystal wit h a long-range quasiperiodic correlation. The D phase is formed with a comp osition close to Al74Ni15Ru11, as determined by energy-dispersive X-ray ana lysis. By means of high-resolution electron microscopy, the structural feat ures of the Al-Ni-Ru D phase, which are obviously different from that of th e AI-Pd D phase (a typical decagonal quasicrystal with 1.6 nm periodicity r eported previously), have been revealed.