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

9704217赫夫纳格尔小角X射线散射是在1-100 nm尺度上研究材料结构的最新技术之一。在这种尺度上研究材料的能力对于理解金属合金微结构的发展以及研究聚合物溶液的结构和动力学都是重要的。SAXS仪器对约翰霍普金斯大学关于金属玻璃、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。其中一个项目寻求通过改进对相分离和晶化动力学的了解来开发新的块状金属玻璃材料和工艺。另一个项目探索纳米晶复合材料的结构-性能关系，纳米晶复合材料由纳米级金属晶体分散在非晶态金属基质中组成。SAXS设备将为这项研究提供一种手段，研究金属玻璃的纳米级结构，这是相变和微观机械行为的关键区域。用SAXS仪器检测的另一类材料是软材料，如复杂的流体和聚合物。复合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能力对这项研究计划至关重要，特别是对于不适用于光散射的高度集中的系统，SAXS设备将提供一种调查并最终了解结构和动力学之间耦合的手段。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类体系中的构象。超临界溶剂能够溶解一系列聚合物，如含氟聚合物、无规共聚物和嵌段共聚物。本课程的重点将放在这些超临界溶剂系统中聚合物或超分子组件的结构上。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。它还将为目前的小角中子散射(SANS)和反常小角X射线散射(ASAXS)研究提供必要的补充，这些研究虽然对这些计划至关重要，但就仪器可用性而言是有限的。***

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. ***