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首页> 外文期刊>Journal of Alloys and Compounds: An Interdisciplinary Journal of Materials Science and Solid-state Chemistry and Physics >Microstructural evolution and improved hydrogenation-dehydrogenation kinetics of nanostructured melt-spun Mg-Ni-Mm alloys
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Microstructural evolution and improved hydrogenation-dehydrogenation kinetics of nanostructured melt-spun Mg-Ni-Mm alloys

机译：纳米结构熔纺Mg-Ni-Mm合金的微观组织演化和改善的加氢脱氢动力学

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摘要

The microstructural evolution of as-quenched ribbons and bail-milled hydrides of the Mg-10Ni-2Mm alloy was studied by TEM. These studies showed a refinement of the microstructures during the applied processing and a nucleation of MmMg_(12) intermetallic at the grain boundaries of Mg and Mg_2Ni. The interface between MmMg_(12) and Mg_2Ni is semi-coherent, with an ordered repetition of the consistent atomic arrangements. The kinetics of H-absorption/desorption is improved due to the fast hydrogen diffusion in the nanograms, thus, providing paths for H-exchange. TEM studies showed (a) stability of the nano-sized grains in the ball-milled Cu-1000 (the surface velocity of the copper wheel: 1000 rpm) sample that underwent cycling of hydrogen desorption and absorption during heating to 350 °C; (b) formation of MmH_(3-x) hydride from MmMg_(12) and its preferential location at grain boundaries of MgH_2. Clearly, MmH_(3-x) and Mg_2NiH_4 act as nucleation centres to initiate the formation of MgH_2, thus, promoting hydrogen absorption by the Mg alloys. Pressure-composition-temperature diagrams show the presence of two plateaux, Mg-MgH_2 and Mg_2Ni-Mg_2NiH_4. The MgH_2 plateau showed no hysteresis and practically no slope, while the plateau for Mg_2NiH_4 exhibited both a pronounced hysteresis and a slope, particularly for the nanocrystalline sample. The maximum hydrogen storage capacity of the nanocrystalline sample was higher than that of the microcrystalline one.
机译：用TEM研究了Mg-10Ni-2Mm合金淬火后的带状组织和保释状的氢化物的组织演变。这些研究表明，在应用过程中微结构的细化和Mg和Mg_2Ni晶界处的MmMg_（12）金属间化合物成核。 MmMg_（12）与Mg_2Ni之间的界面是半相干的，一致的原子排列有序地重复。由于纳克中氢的快速扩散，提高了H吸收/解吸的动力学，从而为H交换提供了途径。 TEM研究表明：（a）球磨的Cu-1000样品（铜轮的表面速度：1000 rpm）中的纳米晶粒的稳定性在加热至350°C的过程中经历了氢的脱附和吸收循环。 （b）由MmMg_（12）形成MmH_（3-x）氢化物及其在MgH_2晶界的优先位置。显然，MmH_（3-x）和Mg_2NiH_4作为成核中心来引发MgH_2的形成，从而促进了Mg合金的氢吸收。压力-组成-温度图显示了两种平稳态Mg-MgH_2和Mg_2Ni-Mg_2NiH_4的存在。 MgH_2平台没有滞后，几乎没有斜率，而Mg_2NiH_4的平台既有明显的滞后又有斜率，特别是对于纳米晶体样品。纳米晶体样品的最大储氢能力高于微晶样品。

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