TY - JOUR
T1 - High-pressure viscosity of liquid Fe and FeS revisited by falling sphere viscometry using ultrafast X-ray imaging
AU - Kono, Yoshio
AU - Kenney-Benson, Curtis
AU - Shibazaki, Yuki
AU - Park, Changyong
AU - Shen, Guoyin
AU - Wang, Yanbin
N1 - Funding Information:
We acknowledge two anonymous reviewers for valuable comments. The experiments were carried out at the Sector 16-BM-B, HPCAT at the Advanced Photon Source. This research is supported by DOE-NNSA under Award Nos. DE-NA0001974 and DOE-BES under Award No. DE-FG02-99ER45775 . The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. YW acknowledges NSF Grant EAR-1214376 .
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/4/1
Y1 - 2015/4/1
N2 - 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. °C and 1-6 GPa, suggesting that sulfur markedly decreases viscosity in liquid Fe.
AB - 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. °C and 1-6 GPa, suggesting that sulfur markedly decreases viscosity in liquid Fe.
KW - High pressure
KW - Liquid iron
KW - Liquid iron sulfide
KW - Liquid structure
KW - Viscosity
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U2 - 10.1016/j.pepi.2015.02.006
DO - 10.1016/j.pepi.2015.02.006
M3 - Article
AN - SCOPUS:84924070599
VL - 241
SP - 57
EP - 64
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
SN - 0031-9201
ER -