In-situ Synchrotron X-ray Diffraction Study of Quartz Deformation

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。非技术解释：预测结晶固体对导致其改变形状的力的反应的能力，或者换句话说，变形，在许多领域都很重要，包括材料工程，冶金学和地球科学，并应用于从金属成型到造山等问题。该研究项目将研究与地球内部相关的温度和压力下石英岩（一种常见的含石英岩石）的变形行为。我们将结合原位同步加速器x射线衍射，计算机模拟和样品分析来研究岩石中特定晶体群的行为，这将提高我们对岩石中晶体群的行为如何整合以产生岩石整体行为的理解。我们的研究结果将对理解地质过程最有用，比如产生山脉的地质过程或确定地壳中地震发生的位置。然而，由于使石英晶体变形的变形机制与金属和陶瓷中的变形机制相同，我们预计我们的研究结果也将有助于解决更普遍的问题，这些问题将应用于一系列工程问题。本项目申请的大部分资金将用于支持青年科学家（包括本科生、研究生和研究生）的教育，支持他们参与前沿研究。技术说明：本项目将采用同步x射线衍射法对石英进行高压、高温变形实验，结合弹塑性自一致建模和仔细检查样品微观结构，了解变形过程中晶粒群之间的应力分布。实验的目的是让我们检查各种变形机制和晶粒相互作用在产生多晶石英的整体流变行为中的相对作用。此外，将显微结构分析与同步加速器衍射观测相结合，将大大有助于对高压变形实验所得衍射数据的理解和解释。因此，本研究的结果将对使用大体积高压仪器制作的其他土材料的变形研究以及利用相同类型衍射数据的金刚石anvilcell （DAC）的超高压变形研究产生影响和应用。该结果也将对工程陶瓷和金属的中子和x射线衍射研究产生影响。

This award is funded under the American Recovery and Reinvestment Act of2009 (Public Law 111-5).Non-technical explanation:The ability to predict the response of crystalline solids to forces thatcause them to change shape, or in other words deform, is important in manyareas including materials engineering, metallurgy and geoscience and hasapplications to problems ranging from metals forming to mountain building. This research project will investigate the deformation behavior ofquartzite, a common quartz-bearing rock, at the temperatures and pressuresrelevant to the earth's interior. We will use a combination of in-situsynchrotron x-ray diffraction, computer based simulations and sampleanalysis to study the behavior of specific groups of crystals within therock which will improve our understanding of how the behavior of groups ofcrystals within a rock integrate to produce the overall behavior of therock. Our results will be most useful in understanding geologicalprocesses such as those that produce mountains or determine where inEarth's crust, earthquakes occur. However, because the deformationmechanisms that allow quartz crystals to deform are the same as those thatoperate in metals and ceramics, we anticipate that our results will alsoshed light on more general questions that have applications to a range ofengineering problems. The majority of the funding requested for thisproject will support the education of young scientists includingundergraduate, graduate and post-graduate scholars by supporting them asthey participate in cutting edge research.Technical explanation:This project will use in-situ synchrotron x-ray diffraction from highpressure, high temperature deformation experiments on quartz combined withelastic plastic self consistent modeling and careful examination of samplemicrostructures to learn about the distribution of stress between grainpopulations during deformation. The experiments are designed to allow usto examine the relative roles of various deformation mechanisms andgrain-grain interactions in generating the overall rheological behavior ofpolycrystalline quartz. In addition, the combination of microstructuralanalysis with synchrotron diffraction observations will add a great dealto the understanding and interpretation of diffraction data gathered fromhigh pressure deformation experiments. Therefore the results from thisstudy will have implications for and applications to deformation studiesof other earth materials made with large volume high pressure apparatus,as well as ultrahigh pressure deformation studies in the diamond anvilcell (DAC) that utilize the same type of diffraction data. The resultswill also have implications for neutron and x-ray diffraction studies ofengineering ceramics and metals.