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In situ X-ray diffraction measurement of shock-wave-driven twinning and lattice dynamics

机译：冲击波驱动孪晶和晶格动力学的原位X射线衍射测量

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摘要

Pressure-driven shock waves in solid materials can cause extreme damage and deformation. Understanding this deformation and the associated defects that are created in the material is crucial in the study of a wide range of phenomena, including planetary formation and asteroid impact sites(1-3), the formation of interstellar dust clouds(4), ballistic penetrators(5), spacecraft shielding(6) and ductility in high-performance ceramics(7). At the lattice level, the basic mechanisms of plastic deformation are twinning (whereby crystallites with a mirror-image lattice form) and slip (whereby lattice dislocations are generated and move), but determining which of these mechanisms is active during deformation is challenging. Experiments that characterized lattice defects(8-11) have typically examined the microstructure of samples after deformation, and so are complicated by post-shock annealing(12) and reverberations. In addition, measurements have been limited to relatively modest pressures (less than 100 gigapascals). In situ X-ray diffraction experiments can provide insights into the dynamic behaviour of materials(13), but have only recently been applied to plasticity during shock compression(14-17) and have yet to provide detailed insight into competing deformation mechanisms. Here we present X-ray diffraction experiments with femtosecond resolution that capture in situ, lattice-level information on the microstructural processes that drive shock-wave-driven deformation. To demonstrate this method we shock-compress the body-centred-cubic material tantalum-an important material for high-energy-density physics owing to its high shock impedance and high X-ray opacity. Tantalum is also a material for which previous shock compression simulations(18-20) and experiments(8-12) have provided conflicting information about the dominant deformation mechanism. Our experiments reveal twinning and related lattice rotation occurring on the timescale of tens of picoseconds. In addition, despite the common association between twinning and strong shocks(21), we find a transition from twinning to dislocation-slip-dominated plasticity at high pressure (more than 150 gigapascals), a regime that recovery experiments cannot accurately access. The techniques demonstrated here will be useful for studying shock waves and other high-strain-rate phenomena, as well as a broad range of processes induced by plasticity.
机译：固体材料中压力驱动的冲击波会导致极端的损坏和变形。了解这种变形以及材料中产生的相关缺陷对于研究各种现象至关重要，这些现象包括行星形成和小行星撞击点（1-3），星际尘埃云的形成（4），弹道穿透器（5），航天器屏蔽（6）和高性能陶瓷的延展性（7）。在晶格水平上，塑性变形的基本机制是孪晶（从而形成具有镜像晶格形式的微晶）和滑移（从而产生并移动晶格位错），但是要确定在变形过程中哪种机制有效。表征晶格缺陷的实验（8-11）通常检查变形后样品的微观结构，因此受到震后退火（12）和混响的影响。此外，测量仅限于相对适中的压力（小于100吉帕斯卡）。原位X射线衍射实验可以提供有关材料动态行为的见解（13），但直到最近才将其应用于冲击压缩过程中的可塑性（14-17），并且尚未提供有关竞争变形机制的详细见解。在这里，我们介绍了飞秒分辨率的X射线衍射实验，该实验在驱动冲击波驱动变形的微结构过程中捕获了原位，晶格级信息。为了证明这种方法，我们对以人体为中心的立方材料钽进行了震击压缩，钽是高能量密度物理学的重要材料，因为它具有较高的耐震性和较高的X射线不透明度。钽也是一种材料，以前的冲击压缩模拟（18-20）和实验（8-12）为此提供了有关主要变形机制的相互矛盾的信息。我们的实验揭示了孪生和相关的晶格旋转发生在数十皮秒的时间尺度上。此外，尽管孪生和强烈冲击之间存在共同的联系（21），但我们发现在高压（超过150吉帕斯卡）下，孪生转变为以位错滑移为主的可塑性，而恢复实验无法准确获得这种状态。这里展示的技术将对研究冲击波和其他高应变率现象以及可塑性引起的广泛过程很有用。

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  • 来源
    《Nature》 |2017年第7677期|496-499|共4页
  • 作者

    Wehrenberg C. E.; McGonegle D.; Bolme C.; Higginbotham A.; Lazicki A.; Lee H. J.; Nagler B.; Park H. -S.; Remington B. A.; Rudd R. E.; Sliwa M.; Suggit M.; Swift D.; Tavella F.; Zepeda-Ruiz L.; Wark J. S.;

  • 作者单位

    Lawrence Livermore Natl Lab, 7000 East Ave, Livermore, CA 94550 USA;

    Univ Oxford, Dept Phys, Clarendon Lab, Parks Rd, Oxford OX1 3PU, England;

    Los Alamos Natl Lab, Bikini Atoll Rd,SM-30, Los Alamos, NM 87545 USA;

    Univ York, Dept Phys, York YO10 5DD, N Yorkshire, England;

    Lawrence Livermore Natl Lab, 7000 East Ave, Livermore, CA 94550 USA;

    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA;

    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA;

    Lawrence Livermore Natl Lab, 7000 East Ave, Livermore, CA 94550 USA;

    Lawrence Livermore Natl Lab, 7000 East Ave, Livermore, CA 94550 USA;

    Lawrence Livermore Natl Lab, 7000 East Ave, Livermore, CA 94550 USA;

    Univ Oxford, Dept Phys, Clarendon Lab, Parks Rd, Oxford OX1 3PU, England;

    Univ Oxford, Dept Phys, Clarendon Lab, Parks Rd, Oxford OX1 3PU, England;

    Lawrence Livermore Natl Lab, 7000 East Ave, Livermore, CA 94550 USA;

    SLAC Natl Accelerator Lab, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA;

    Lawrence Livermore Natl Lab, 7000 East Ave, Livermore, CA 94550 USA;

    Univ Oxford, Dept Phys, Clarendon Lab, Parks Rd, Oxford OX1 3PU, England;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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