In-situ Observtion of Annealing Behaviors of Bulk Metallic Polycrystals

技术概要：多晶体是在极端和普通环境中使用的普遍存在的材料，从核反应堆和涡轮机叶片到结构支撑和运输基础设施。直到最近，还不可能在空间上解析多晶材料内部深处的相关结构细节，因为它们响应于例如热退火而演变。在这个项目中，聚焦在阿贡国家实验室的高级光子源产生的高能X射线将与国家科学基金会的TeraGrid超级计算机网络结合使用，以非破坏性地测量和重建三维多晶体的晶体取向场。在有序的材料中，当它们在退火过程中演变时，将观察到晶粒系综;统计和局部信息将从大型微观结构数据集中提取。在具有显著缺陷含量的材料中，将有可能测量晶粒内的取向梯度，并观察缺陷结构在材料达到较低能量、更有序状态时的移动和演变。这项资助下的工作将促进对多晶材料如何应对高温的理解。研究结果将被用于进一步了解以前隐藏的现象，目标是建立具有预测能力的验证模型。非技术性总结：由于多晶体在工业、能源和国防系统中的应用如此广泛，因此提高对多晶体微观结构在退火过程中如何演变的基本科学认识的潜在经济和能源影响可能是巨大的。该项目的实验将使用能源部的国家用户设施（阿贡国家实验室的先进光子源，世界上最强大的X射线源之一），而数据分析将涉及国家科学基金会的TeraGrid超级计算机网络。由此产生的数据将提供一个独特的视角来看待与构建材料行为理论相关的量。研究的一个主要目标是将所获得的理解应用于具有改进性能的材料的开发。研究生和本科生，与教师和博士后研究人员从科学，数学和工程部门的工作，将得到指导。他们将熟练掌握X射线科学，可以应用于许多材料问题，并将体验高性能计算世界。通过与建模社区的互动，实验计划的广泛影响将大大增加。

TECHNICAL SUMMARY: Polycrystals are ubiquitous materials that serve in extreme and mundane environments, ranging from nuclear reactors and turbine blades to structural supports and transportation infrastructure. Until recently, it has not been possible to spatially resolve relevant structural details deep inside polycrystalline materials as they evolve in response to, for example, thermal annealing. In this project focused high energy x-rays generated at the Advanced Photon Source at the Argonne National Laboratory will be used in combination with the National Science Foundation's TeraGrid supercomputer network to non-destructively measure and reconstruct the crystallographic orientation field of polycrystals in three dimensions. In well-ordered materials, crystalline grain ensembles will be observed as they evolve during annealing; both statistical and local information will be extracted from large microstructure data sets. In materials with significant defect contents, it will be possible to measure orientation gradients within grains and to watch defect structures move and evolve as the material reaches a lower energy, more ordered state. Work under this grant will advance understanding of how polycrystalline materials respond to high temperatures. The results will be used to develop improved understanding of previously hidden phenomena with the goal of establishing validated models with predictive power.NON-TECHNICAL SUMMARY: Because polycrystals are so broadly used in industrial, energy, and defense systems, the potential economic and energy impact of improved basic scientific understanding of how polycrystalline microstructures evolve during annealing can be huge. The experiments in this project will use a Department of Energy national user facility (the Advanced Photon Source at Argonne National Laboratory, one of the world's most powerful x-ray sources) while the analysis of data will involve the National Science Foundation's TeraGrid supercomputer network. The resulting data will provide a unique look at the quantities that are relevant for building theories of how materials behave. A major objective of the research is to apply the understanding gained to the development of materials with improved properties. Graduate and undergraduate students, working with faculty and post-doctoral researchers from science, mathematics and engineering departments, will be mentored. They will become skilled in x-ray science that can be applied to many materials problems and will experience the high-performance computing world. The broad impact of the experimental program will be substantially increased through interactions with the modeling community.