Effect of yttrium on microstructure and quasicrystal's formation in as-cast Mg-Zn-Y alloy

Stable icosahedral Zn60Mg3O10 quasicrystals were prepared by as-cast method. On this base, the feasibility to prepare quasi crystalline reinforced low-density magnesium alloy was also discussed. The microstructure, the composition and the phases of the as-cast Mg-Zn-Y alloy were analyzed by optical microscope, SEM and EDS. The constituent phases were identified by XRD and quasi crystal structure was identified by TEM. Analyzing the different component of alloys, especially the mole fraction of yttrium, can lead quasi crystals that have different micro morphologies, amounts and distributing. Results show that the I-phases directly nucleate and grow from melt of cooling Mg-Zn-Y ternary alloys; the granularity, the circular-degree and the distributing-leveling of the quasi crystalline were improved with the increasing of yttrium's contents.