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

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。非技术解释：预测晶体固体对力的反应的能力在许多领域都很重要，包括材料工程、冶金和地球科学，从金属成形到山体建筑。这项研究项目将研究一种常见的含石英岩石--石英岩在与地球内部相关的温度和压力下的变形行为。我们将使用现场同步X射线衍射、基于计算机的模拟和样品分析相结合的方法来研究岩石中特定晶体组的行为，这将提高我们对岩石中晶体组的行为如何结合起来产生岩石整体行为的理解。我们的结果将对理解地质过程最有用，例如那些形成山脉的过程或确定地壳中哪里发生地震的过程。然而，由于允许石英晶体变形的变形机制与运行在金属和陶瓷中的变形机制相同，我们预计我们的结果也将阐明更一般的问题，这些问题适用于一系列工程问题。该项目申请的大部分资金将通过支持青年科学家参与尖端研究来支持他们的教育，包括本科生、研究生和研究生学者。技术解释：该项目将使用高压现场同步X射线衍射、石英高温变形实验以及弹塑性自洽模型和仔细检查样品微观结构，以了解变形过程中颗粒群体之间的应力分布。这些实验的目的是让我们能够检验各种变形机制和颗粒-颗粒相互作用在产生多晶石英整体流变行为中的相对作用。此外，显微组织分析与同步加速器衍射观测的结合将极大地促进对高压变形实验中所收集的衍射数据的理解和解释。因此，这项研究的结果将对用大体积高压装置制作的其他地球材料的变形研究以及利用相同类型的衍射数据的金刚石棒(DAC)中的超高压变形研究具有指导意义和应用价值。这一结果也将对工程陶瓷和金属的中子和X射线衍射研究具有重要意义。

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.