High-pressure viscosity of liquid Fe and FeS revisited by falling sphere viscometry using ultrafast X-ray imaging
High-pressure viscosity of liquid Fe and FeS revisited by falling sphere viscometry using ultrafast X-ray imaging
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DOI：
10.1016/j.pepi.2015.02.006
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发表时间：
2015-04-01
影响因子：
2.3
通讯作者：
Wang, Yanbin
中科院分区：
文献类型：
--
作者：
Kono, Yoshio;Kenney-Benson, Curtis;Wang, Yanbin
液态 Fe 和 FeS 的粘度已被广泛研究，产生的结果相差几乎十倍（液态 Fe 为 2.4-23.7 mPa s，液态 FeS 为 3.6-17.9 mPa s，Fe-S 共晶成分为 7.4-35.6 mPa s），这可能是由于以前在使用 X 射线进行落球测量时使用的慢速相机（通常为 30-60 帧/秒）的分辨率较低。射线照相。在这里，我们使用最近开发的超快 X 射线成像重新审视了高达 6.4 GPa 的液态 Fe 和 FeS 的粘度。在这项研究中，我们以 500 帧/秒的速率对下落球体进行成像，这比之前的粘度测量快了约 10 倍。我们的测量表明，终端速度仅在有限的下落距离区域内实现，并且使用足够高速的 X 射线成像进行大量过采样对于准确确定终端速度和所得粘度至关重要。在压力至 6.4 GPa 时，沿着各自的熔化曲线，我们获得了液态 Fe 的粘度为 6.1-7.4 mPa s，液态 FeS 的粘度为 4.7-5.7 mPa s。沿着各自的熔化曲线，液态 FeS 的粘度比液态 Fe 的粘度低约 25-35%，在 2 至 6.4 GPa 之间。经过校正Fe和FeS之间不同熔化温度对粘度的影响，我们发现在1800℃和1-6 GPa下，液态FeS的粘度比液态Fe低31-42%，这表明硫显着降低了液态Fe的粘度。 (C) 2015 Elsevier B.V. 保留所有权利。
The viscosity of liquid Fe and FeS has been extensively studied, yielding results differing by almost a factor of ten (2.4-23.7 mPa s for liquid Fe, 3.6-17.9 mPa s for liquid FeS, and 7.4-35.6 mPa s for the Fe-S eutectic composition), possibly due to the low resolution of slow cameras previously employed (typically 30-60 frames/s) in falling sphere measurements using X-ray radiography. Here we revisit the viscosity of liquid Fe and FeS up to 6.4 GPa using recently developed ultrafast X-ray imaging. In this study, we imaged the falling spheres at a rate of 500 frames/s, which is around 10 times faster than previous viscosity measurements. Our measurements showed that terminal velocity is achieved only in a limited region of falling distance, and that substantial oversampling, using sufficiently high-speed X-ray imaging, is essential to accurately determine the terminal velocity and the resulting viscosity. We obtained a viscosity of 6.1-7.4 mPa s for liquid Fe and 4.7-5.7 mPa s for liquid FeS at pressures to 6.4 GPa along their respective melting curves. The viscosity of liquid FeS is about 25-35% lower than that of liquid Fe between around 2 and 6.4 GPa along their respective melting curves. After correction for the effect of different melting temperatures between Fe and FeS on viscosity, we found that viscosity of liquid FeS is 31-42% lower than that of liquid Fe at 1800 degrees C and 1-6 GPa, suggesting that sulfur markedly decreases viscosity in liquid Fe. (C) 2015 Elsevier B.V. All rights reserved.