Coupled Nucleation, Nanostructure Formation and Hydrogen Storage in Metallic Glasses and Quasicrystals

技术支持：成核过程比通常假设的要复杂，必须适当考虑长程扩散和界面附着的随机通量之间的耦合。最近的研究，包括PI的研究表明，序参数波动，如那些基础的化学，结构和磁有序也可以耦合与成核相关联的序参数波动。除了他们的基本利益，这些结果表明，增强纳米结构细化是可能的，通过提高理解这种成核行为。为了更好地理解成核过程中的耦合过程及其改善微观结构细化的潜力，本项目将通过宽角和小角X射线衍射、高分辨率、能量过滤和波动透射电子显微镜、EXAFS和原子探针测量来确定所选Ti/Zr基、Co/Fe基和Mg基金属玻璃的局部原子结构。该数据将与玻璃形成和结晶动力学相关，通过差示扫描量热法和电阻率测量以及基于TEM的时间依赖性成核研究来确定。研究还将继续探讨扩散对成核行为的影响。的循环特性和起源的高压平台将被确定为散装和纳米结构的i（TiZrNi），以评估其潜在的有用性作为储氢材料。非技术性：这些研究的结果将具有广泛的基础和技术意义，包括储氢、更深入地了解相变和改进对纳米结构生产的控制。Ti/Zr准晶可以帮助促进向氢基传输系统的过渡。该研究具有重要的教育意义，为研究生和本科生提供培训，并为当地高中学生提供材料科学理论和实验方法的经验。PI和他的研究生将向学生和教师介绍研究成果，并直接与学生合作，使他们接触到科学职业的可能性。

TECHNICAL: Nucleation processes are more complex than often assumed, and proper account must be taken of the coupling between the stochastic fluxes of long-range diffusion and interfacial attachment. Recent studies, including those by PI indicate that order-parameter fluctuations such as those that underlie chemical, structural, and magnetic ordering can also couple with the order parameter fluctuations associated with nucleation. In addition to their basic interest, these results demonstrate that enhanced nanostructural refinement is possible by an improved understanding of this nucleation behavior. To better understand coupled process in nucleation and their potential for improved microstructure refinement, this project will determine the local atomic structure of select Ti/Zr-based, Co/Fe-based and Mg-based metallic glasses by wide and small angle x-ray diffraction; high resolution, energy filtered and fluctuation transmission electron microscopy; EXAFS; and atom probe measurements. This data will be correlated with glass formation and the crystallization kinetics, determined by differential scanning calorimetry and electrical resistivity measurements and by TEM based studies of time-dependent nucleation. Research will also continue to probe the influence of diffusion on nucleation behavior. The cycling characteristics and origin of the high-pressure plateau will be determined for bulk and nanostructured i(TiZrNi) to evaluate its potential usefulness as a hydrogen storage material. NON-TECHNICAL: The results from these studies will be of broad basic and technological interest including hydrogen storage, a deeper understanding of phase transitions and improved control over nanostructure production. The Ti/Zr quasicrystals could help facilitate the transition to a hydrogen-based transportation system. The research has a significant educational importance, providing training to graduate and undergraduate students, and experience to local high school students in the theoretical and experimental methods of materials science. PI and his graduate students will give presentations of research results to the students and teachers and work directly with the students to expose them to the possibilities for scientific careers.