Structural and Microstructural Studies of Ti/Zr- and Al-Based Quasicrystal, Approximants and Metallic Glasses

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0072787 Kelton This research explores the formation and structure of titanium-zirconium based quasicrystals. There are several facets to the program: (1) elastic neutron scattering and NMR studies of quasicrystals that are partially loaded with hydrogen and deuterium; (2) examination of the Ti-Zr-Ni phase diagram; (3) the transformation mechanisms of transition phases; and (4) the nucleation and growth characteristics of the crystal metal hydride phases that form during hydrogen cycling. An attempt is made to model and measure quantitatively the time-dependent nucleation rates in selected Ti-Zr glasses that crystallize to nanostructured quasicrystals and crystals. In addition H and D are used as structural probes for stable AlPdMn and MgZn-rare earth quasicrystals to test proposed structural models.%%%The results of these studies are of value to the quasicrystal scientific community and the broader materials community. Insight gained from the crystallization studies leads to refinements of new models for nucleation and improved processing capabilities for the production of nanostructured materials.***