Carbon transformations in rapidly solidified nickel–carbon ribbon
Carbon transformations in rapidly solidified nickel–carbon ribbon
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DOI：
10.1016/j.carbon.2021.08.037
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发表时间：
2021-08
期刊：
影响因子：
10.9
通讯作者：
G. Greenidge;S. Price;J. Erlebacher
中科院分区：
文献类型：
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作者：
G. Greenidge;S. Price;J. Erlebacher
我们报告了碳的结构转变，通过熔融纺丝和随后的退火的镍碳合金。通过快速凝固，获得了碳在镍带中的亚稳态固溶度，凝固速率高达1.6 × 106 K/s。发现过量的碳原子溶解在镍晶格中，导致在70 m/s切向轮速度下旋转的合金的高达1.4%的应变。高温热处理导致碳从带状物自由表面上的镍晶格中沉淀，但也导致镍基质内的球形沉淀物的生长，这一效应与体扩散驱动的奥斯特瓦尔德熟化一致。通过金属的化学溶解从条带中挖掘出碳，并通过电子显微镜和拉曼光谱进行表征。我们发现，从快速淬火带中析出的碳的微观结构可以通过改变碳含量从4到12原子。%的前体中，并在400至1200 °C的温度下对带进行退火。通过这两个参数的逐步变化，我们将具有203 m2/g的高BET表面积的无定形碳纳米球依次转化为厚的、高度结晶的石墨薄片，其符合初生带的形状。
We report the structural transformations of carbon via the melt spinning and subsequent annealing of nickel-carbon alloys. We attained metastable solid solubility of carbon in nickel ribbon by achieving a rapid solidification rate of up to 1.6 × 106K/s. Excess carbon atoms were found to be dissolved in the nickel lattice causing up to 1.4% strain for an alloy spun at 70 m/s tangential wheel speeds. High temperature heat treatments led to precipitation of carbon from the nickel lattice on the ribbon free surfaces but also led to growth of spherical precipitates within the nickel matrix, an effect consistent with bulk diffusion-driven Ostwald ripening. Carbon was excavated from the ribbons via chemical dissolution of the metal and characterized by electron microscopy and Raman spectroscopy. We found that the microstructure of carbon precipitated from the rapidly quenched ribbon could be tuned by varying the carbon content from 4 to 12 at. % in the precursor and annealing the ribbon at temperatures that ranged from 400 to 1200 °C. Via the step-wise variation of these two parameters, we sequentially transformed amorphous carbon nanospheres with a high BET surface area of 203 m2/g into thick, highly crystalline flakes of graphite that conformed to the shape of the as-spun ribbon.