The formation, structure, and hydrogen storage properties of titanium/zironcium/hafnium based quasicrystals and related phases

Previous studies of hydrogen storage in Ti-Zr-Ni quasicrystals are reviewed and expanded. Based on the new results presented in this thesis hydrogen may be used as a probe of local structure if elastic and electronic interactions of the hydrogen atom with the lattice and other hydrogen atoms in the lattice are better understood.; As-cast and as-quenched phases found in the Ti-Hf-Ni ternary system are surveyed. A high order (3/2) rational approximant to the quasicrystal and a metallic glass were some of the phases found in the as-quenched survey. These two phases were further studied showing that the 3/2 rational approximant is metastable, transforming to a stable Ti2Ni-type phase upon heating. The metallic glass found in this system has a 65°C separation between the glass transition and the first crystallization event to a nano-domained icosahedrally ordered phase.; Hydrogenation studies of the 3/2 rational approximant and the metallic glass in Ti-Hf-Ni were also performed. These studies show that the structures around the hydrogen atoms are similar in both phases. The structures are also similar to the Ti-Zr-Ni quasicrystals.; Other hydrogen storage methods were explored. Mechanically alloyed Ti-Zr-Ni quasicrystals and metallic glasses have a potential to be used as hydrogen storage materials. These mechanically alloyed phases do not need to have their surfaces prepared or activated for hydrogenation to occur, and show little formation of the irreversible hydride phase. Pressure composition isotherms at higher pressures than have been performed before on these alloys were examined. This required a new high-pressure Sievart's type apparatus to be built. The initial results from pressure composition isotherm measurements show that there is another pressure plateau, above the one previously found at low pressures. This higher pressure plateau is a region of pressure and temperature suitable for hydrogen storage applications.