Effect of composition on the i-phase cell parameter of Ti–(Zr,Cu)–Ni alloys

Quasicrystalline (i-phase) Ti–Zr–Ni samples were obtained using the melt-spinning technique, where the Ti/Zr ratio ranged from 1 to 3, while the Ni content remained nearly constant, varying between 17 and 20 at. %. We replaced the Zr with 3 and 5 at. % of Cu in order to test the i-phase-forming ability of the samples, which were all subsequently hydrided from the gas phase at 45 bar and 300 °C for 1000 min. We then made XRD analyses of the as-spun and loaded samples in order to determine the influence of the composition and the absorbed hydrogen content on the cell parameter of the i-phase. An almost linear decrease of this parameter with the ([Ti] + [Cu])/[Zr] ratio was found for the as-prepared and hydrided samples, where the slope of the linear fit is preserved after hydrogenation, but with about 6% higher values due to the expansion of the quasilattice. XPS analyses of the melt-spun i-Ti45Zr35Ni17Cu3 revealed an oxide-layer thickness of 4 nm. A TEM investigation revealed that the size of the i-phase grains on the wheel side of the ribbon was approximately five times smaller than on the bright side, as a result of the higher cooling rate and the resulting faster nucleation rate.