Coherent X-Ray Scattering Studies of Phase Transitions in Metals

金属相变的相干 X 射线散射研究

• 批准号: 0508630
• 负责人: Karl Ludwig
• 金额: $ 30万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0508630&HistoricalAwards=false
• 关键词: Coherent; Ray; Scattering; Studies; Phase

Technical: X-ray scattering/diffraction has long been a primary tool for investigating the atomic structure and evolution of materials. Traditional x-ray scattering uses photon beams that have effective coherence lengths significantly smaller than the size of the beam itself. The availability of high brilliance hard x-ray beams from 3rd generation synchrotron sources, however, has opened the possibility of making small x-ray beams (typically of order 10 mm in diameter) that exhibit significant coherence throughout the scattering volume. Currently available hard x-ray beams enable some of the techniques traditionally used in the optical regime to now be used in the hard x-ray regime. This program expands the applications of coherent x-ray scattering to investigate dynamics, kinetics and microscopic reversibility in metal and alloy phase transitions. It will examine microscopic reversibility and memory in alloys exhibiting displacive phase transitions, including the Cu-Zn-Al shape memory alloys. It will also examine the relationships between fluctuations, defect pinning and kinetics in these systems as well as in ordering alloys. Finally, the development of heterodyne techniques will be examined for the study of fluctuation dynamics in cases where the inherent sample scattering is relatively weak and diffuse. Non-Technical: This research program will improve understanding of nanoscale dynamics, i.e. how atoms move on the nanometer length scale. Such knowledge is important for understanding and developing advanced materials that will form the basis of future communications, computing, chemical processing and other industries. As part of this research program, students at the graduate, undergraduate and high school levels will be involved in learning about new x-ray techniques and materials issues that are at the forefront of current materials research. Through continuing collaborations with scientists at other institutions, both inside and outside the US, these students will have an outstanding opportunity to see a variety of research environments.

技术：X 射线散射/衍射长期以来一直是研究原子结构和材料演化的主要工具。 传统的 X 射线散射使用有效相干长度远小于光束本身尺寸的光子束。 然而，第三代同步加速器源的高亮度硬 X 射线束的出现，开启了制造小型 X 射线束（直径通常为 10 毫米量级）的可能性，这些 X 射线束在整个散射体积中表现出显着的相干性。 当前可用的硬X射线束使得传统上在光学领域中使用的一些技术现在能够在硬X射线领域中使用。 该项目扩展了相干 X 射线散射的应用，以研究金属和合金相变的动力学、动力学和微观可逆性。 它将检查具有位移相变的合金（包括 Cu-Zn-Al 形状记忆合金）的微观可逆性和记忆性。 它还将检查这些系统以及订购合金中的波动、缺陷钉扎和动力学之间的关系。 最后，将检查外差技术的发展，以研究固有样本散射相对较弱和扩散的情况下的涨落动力学。非技术性：该研究计划将增进对纳米级动力学的理解，即原子如何在纳米长度尺度上移动。 这些知识对于理解和开发先进材料非常重要，这些材料将成为未来通信、计算、化学加工和其他行业的基础。 作为该研究项目的一部分，研究生、本科生和高中生将参与学习新的 X 射线技术和当前材料研究前沿的材料问题。 通过与美国国内外其他机构的科学家持续合作，这些学生将有绝佳的机会看到各种研究环境。