Preparation Of TiZrNi Quasicrystal Structure, Preparation Of Thin Films And Their Absorption Behavior Of Deuterium And Solid Helium

Tritium as an important strategic resource, in terms of the neutron generator and fusion energy development, has been widely used. Tritium storage is a key part of tritium applications. In order to improve the usage and storage lifetime of tritium film materials with low pressure platform, the fundamental researches, including structure, film preparation, deuterium absorption and helium storage of TiZrNi quasicrystalline, were studied. Four parts are in this work:(1)The theoretical analyses of atomic occupancies in TiZrNi quasicrystalline approximant. The interatomic potentials in TiZrNi are constructed by lattice inversion method. Combined with molecular dynamics, the energetic properties of controversial atomic occupied sites in TiZrNi quasicrystalline approximant are discussed and two models of TiZrNi quasicrystalline approximant are proposed; (2)The preparation and characterization of TiZrNi quasicrystalline film. A DC magnetron sputtering method has been successfully employed to prepare TiZrNi quasicrystalline film with favorable density and adhesion, and the two major factors of the formation of quasicrystalline phase in TiZrNi films are analyzed; (3)The deuterium absorption kinetics of TiZrNi quasicrystal film. Using deuterium absorption and desorption test device, the deuterium absorption kinetics of amorphous, quasicrystalline and crystalline TiZrNi-(Pd) films are studied. The differences of reaction rates and absorption capacities in TiZrNi quasicrystalline films with and without Pd coverage are compared. The absorption kinetics mechanisms of TiZrNi quasicrystalline under the two cases are presented; (4)The theoretical analyses of helium behaviors in TiZrNi quasicrystalline approximant. The preferred energy and mechanism of He atoms occupied in tetrahedral interstitial sites of TiZrNi quasicrystalline approximant, the process and related influences of He nucleation and bubble growth are discussed.Through these studies, the structure, film preparation, deuterium absorption and helium storage are further to be understood and some conclusions are followed:(1)The quasicrystalline phase formation in TiZrNi films is mainly affected by the composition and substrate temperature. When the nominal composition of alloy target is Ti34Zr49Ni17, amorphous, quasicrystalline and fcc-(Ti, Zr)2Ni nanocrystalline films with perfect density and adhesion are obtained under different substrate temperatures. C, TiO2 and ZrO2 are found in the first layer, TiO2, ZrO2 and the metal Ti, Zr, Ni mixtures are in the second layer, the final layer in films is metal Ti, Zr and Ni. The oxidation of Zr in TiZrNi films with different crystal types is stronger than that of Ti. The thickness of Ti and Zr oxides in TiZrNi films is amorphous> quasicrystalline> crystalline.(2)Without Pd film, deuterium absorption behaviors in TiZrNi films with different crystal types are substantially similar, and the reaction rates and absorption capacities in such films are relatively lower. Due to the influence of oxide layer in film surface, the deuterium atoms are basically stuck in the films surface with solid solution; With Pd film, deuterium absorption behaviors in TiZrNi films with different crystal types are various. The reaction rates and absorption capacities of amorphous and quasicrystalline TiZrNi films have been greatly improved, and those of crystalline film are maintained at levels without Pd film. Deuterium atoms migrate to the films deeply, the amorphous and quasicrystalline TiZrNi films present two reaction rate characteristics of solid solution and deuterium hydride.(3)From energy views, Zr atoms could lower energy and stabilize structure of W-TiZrNi quasicrystalline approximant. The stability of W-TiZrNi is mainly resulted from the contribution of Zr atoms to phonon density of states in lower frequency; The occupied energy and storage ability of He atoms in tetrahedral interstitial sites of W-TiZrNi show preferences. In different tetrahedral sites, the preferred occupancy of He atom is related to the type and number of metal atoms in the first and second nearest tetrahedral sites. The occupied energy and probability of He atom in tetrahedral sites decrease and increase with the increasements of Zr, Ni atoms, respectively. The types of nearest tetrahedral sites with the strongest and weakest storage abilities of He are Zr4 and Ti3Ni, respectively; The nucleation of He atoms in W-TiZrNi is through absorbing vacancies produced from metal dislocations and other He atoms, He nucleation could be accelerated by higher temperatures; The merger and growth of He bubbles are owing to atomic interdiffusion between bubbles and the growth of He bubbles is needed to meet temperature and distance conditions.