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首页> 外文期刊>ACS applied materials & interfaces >Self-Organized Al2Cu Nanocrystals at the Interface of Aluminum Based Reactive Nanolaminates to Lower Reaction Onset Temperature
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Self-Organized Al2Cu Nanocrystals at the Interface of Aluminum Based Reactive Nanolaminates to Lower Reaction Onset Temperature

机译：铝基反应性纳米层压板界面处的自组织Al2Cu纳米晶体可降低反应起始温度

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Nanoenergetic materials are beginning to play an important role in part because they are being considered as energetic components for materials, chemical, and biochemical communities (e.g., microthermal sources, microactuators, in situ welding and soldering, local enhancement of chemical reactions, nanosterilization, and controlled cell apoptosis) and because their fabrication/synthesis raises fundamental challenges that are pushing the engineering and scientific frontiers. One such challenge is the development of processes to control and enhance the reactivity of materials such as energetics of nanolaminates, and the understanding of associated mechanisms. We present here a new method to substantially decrease the reaction onset temperature and in consequence the reactivity of nanolaminates based on the incorporation of a Cu nanolayer at the interfaces of Al/CuO nanolaminates. We further demonstrate that control of its thickness allows accurate tuning of both the thermal transport and energetic properties of the system. Using high resolution transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry to analyze the physical, chemical and thermal characteristics of the resulting Al/CuO + interfacial Cu nanolaminates, we find that the incorporation of 5 nm Cu at both Al/CuO and CuO/Al interfaces lowers the onset temperature from 550 to 475 degrees C because of the lower-temperature formation of Al-Cu intermetallic phases and alloying. Cu intermixing is different in the CuO/Cu/Al and Al/Cu/CuO interfaces and independent of total Cu thickness: Cu readily penetrates into Al grains upon annealing to 300 degrees C, leading to Al/Cu phase transformations, while Al does not penetrate into Cu. Importantly, theta-Al2Cu nanocrystals are created below 63% wt Cu/Al, and coexist with the Al solid solution phase. These well-defined theta-Al2Cu nanocrystals seem to act as embedded Al+CuO energetic reaction triggers that lower the onset temperature. We show that similar to 10 nm thick Cu at Al/CuO interfaces constitutes the optimum amount to increase both reactivity and overall heat of reaction by a factor of similar to 20%. Above this amount, there is a rapid decrease of the heat of reaction.
机译：纳米能材料开始发挥重要作用，部分原因是它们被认为是材料，化学和生物化学界（例如，微热源，微致动器，原位焊接和钎焊，化学反应的局部增强，纳米灭菌和控制细胞凋亡），并且由于其制备/合成引发了推动工程和科学前沿的基本挑战。这样的挑战之一是开发控制和增强材料反应性的方法，例如纳米层压板的能量学，以及对相关机理的理解。我们在这里提出了一种新的方法，可以大大降低反应的起始温度，从而基于在Al / CuO纳米层压板的界面上掺入Cu纳米层而使纳米层压板的反应性降低。我们进一步证明了对其厚度的控制可以精确调节系统的热传递和能量特性。使用高分辨率透射电子显微镜，X射线衍射和差示扫描量热法分析所得的Al / CuO +界面Cu纳米层压板的物理，化学和热学特性，我们发现在Al / CuO处均掺入5 nm Cu由于Al-Cu金属间相的低温形成和合金化，CuO / Al界面将起始温度从550摄氏度降低到475摄氏度。 Cu互混在CuO / Cu / Al和Al / Cu / CuO界面中是不同的，并且与总Cu厚度无关：在退火至300摄氏度时，Cu容易渗入Al晶粒中，导致Al / Cu相变，而Al没有渗入铜。重要的是，θ-Al2Cu纳米晶体的含量低于63％wt Cu / Al，并与Al固溶体相共存。这些定义明确的theta-Al2Cu纳米晶体似乎充当嵌入的Al + CuO高能反应触发器，降低了起始温度。我们表明，在Al / CuO界面处，类似于10 nm厚的Cu构成最佳量，以同时提高反应性和总反应热，增幅接近20％。超过该量，反应热迅速降低。

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