Acquisition of a Small-Angle X-ray Scattering System for Investigation of Metallic Glasses and Polymer Solutions

小行星9704217 小角X射线散射（SAXS）是研究1 - 100 nm尺度材料结构的最重要技术之一。 在这种规模上研究材料的能力对于理解金属合金微观结构的发展以及研究聚合物溶液的结构和动力学都很重要。 SAXS仪器对约翰霍普金斯的金属玻璃、复杂流体和聚合物溶液的几个研究项目至关重要。 将受益于SAXS仪器的两个主要研究项目涉及大块金属玻璃。 其中一个项目旨在通过提高对相分离和结晶动力学的理解，开发新的大块金属玻璃材料和工艺。 另一个项目探讨纳米晶复合材料的结构-性能关系，该复合材料由纳米尺度金属晶体分散在非晶金属基质中组成。 SAXS设备将通过提供一种研究金属玻璃纳米级结构的手段来促进这项研究，这是相变和微观力学行为的关键领域。 %%% 另一类要用SAXS仪器检查的材料是软材料，如复杂的流体和聚合物。 复杂流体是含有表面活性剂、聚合物、胶体或这些组分的组合的溶液。 本研究的重点是这些系统的结构和动力学。 SAXS的能力对于这项研究计划至关重要，特别是对于光散射不适用的高度集中的系统，SAXS设备将为研究和最终理解结构和动力学之间的耦合提供一种手段。 另一个活跃的研究领域是超临界流体聚合物溶液，其中特别感兴趣的是聚合物在这种系统中的构象。 超临界溶剂能够溶解整个主体的聚合物，例如含氟聚合物、无规共聚物和嵌段共聚物。 该计划的重点将是在这些超临界溶剂系统中的聚合物或超分子组装体的结构。 SAXS仪器将成为研究金属合金和聚合物溶液结构的有力工具。 它还将为当前的小角中子散射（SANS）和异常小角X射线散射（ASAXS）研究提供必要的辅助工具，这些研究对这些计划至关重要，但在仪器可用性方面受到限制。 ***

9704217 Hufnagel Small-angle x-ray scattering (SAXS) is one of the foremost techniques for studying the structure of materials on a scale of 1-100 nm. The ability to study materials on this scale is important both in understanding the development of the microstructure of metallic alloys, as well as for investigating the structure and dynamics of polymer solutions. The SAXS instrument is critically important to several research projects on metallic glasses, complex fluids, and polymer solutions at Johns Hopkins. Two of the primary research projects that will benefit from the SAXS instrument concern bulk metallic glasses. One of these projects seeks to develop new bulk metallic glass materials and processes through an improved understanding of the kinetics of phase separation and crystallization. The other project probes structure-property relationships in nanocrystalline composite materials, which consist of a dispersion of nanometer-scale metallic crystals in an amorphous metallic matrix. The SAXS equipment will contribute to this research by providing a means to study the nanometer-scale structure of metallic glasses, which is a critical regime in both phase transformations and micromechanical behavior. %%% Another class of materials to be examined with the SAXS instrument are soft materials such as complex fluids and polymers. Complex fluids are solutions containing surfactants, polymers, colloids or a combination of these components. The focus of this research is on the structure and dynamics of these systems. SAXS capabilities are crucial to this research program, especially for highly concentrated systems where light scattering is not applicable, The SAXS equipment will provide a means for investigating and ultimately understanding the coupling between structure and dynamics. Another area of active research is supercritical fluid-polymer solutions, where a particular interest is the conformation of polymers in such systems. Supercrit ical solvents are capable of dissolving a whole host of polymers such as fluoropolymers, random copolymers and block copolymers. The emphasis of this program will be on the structure of the polymers or supramolecular assemblies in these supercritical solvent systems. The SAXS instrument will be a powerful tool for investigating the structure of metallic alloys and polymer solutions. It will also provide a necessary adjunct to current small-angle neutron scattering (SANS) and anomalous small-angle x- ray scattering (ASAXS) investigations, which, while crucial to these programs, are limited in terms of instrument availability. ***