The Fe–C system at 5 GPa and implications for Earth’s core
The Fe–C system at 5 GPa and implications for Earth’s core
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DOI：
10.1016/j.gca.2008.06.006
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发表时间：
2008-08
影响因子：
5
通讯作者：
N. Chabot;Andrew J. Campbell;W. F. McDonough;David S. Draper;C. Agee;M. Humayun;Heather C. Watson
中科院分区：
文献类型：
--
作者：
N. Chabot;Andrew J. Campbell;W. F. McDonough;David S. Draper;C. Agee;M. Humayun;Heather C. Watson
地核可能含有C，有人认为地核中的C可以稳定地形成由Fe3C组成的固体内核。我们在5GPa的压力下对Fe-C体系进行了实验研究，并确定了该压力下Fe-C的相图。此外，我们测量了17种微量元素的固体金属/液态金属分配系数，并研究了14种微量元素在Fe3C与液态金属之间的分配行为。固体金属/液态金属分配系数与单一大气研究中发现的相似，表明压力达到5GPa的影响可以忽略不计。所测Fe3C/液态金属分配系数均小于1，表明所有微量元素都倾向于富c液态而不是Fe3C。在一定周期内，Fe3C/液态金属的分配系数随原子半径的减小而减小。特别有趣的是，我们的5GPa Fe-C相图没有显示任何证据表明Fe-Fe3C共晶组成随着压力的增加而向低C含量转变，这是先前内核可能由Fe3C组成的推理的核心。
Earth’s core may contain C, and it has been suggested that C in the core could stabilize the formation of a solid inner core composed of Fe3C. We experimentally examined the Fe–C system at a pressure of 5GPa and determined the Fe–C phase diagram at this pressure. In addition, we measured solid metal/liquid metal partition coefficients for 17 trace elements and examined the partitioning behavior between Fe3C and liquid metal for 14 trace elements. Solid metal/liquid metal partition coefficients are similar to those found in one atmosphere studies, indicating that the effect of pressure to 5GPa is negligible. All measured Fe3C/liquid metal partition coefficients investigated are less than one, such that all trace elements prefer the C-rich liquid to Fe3C. Fe3C/liquid metal partition coefficients tend to decrease with decreasing atomic radii within a given period. Of particular interest, our 5GPa Fe–C phase diagram does not show any evidence that the Fe-Fe3C eutectic composition shifts to lower C contents with increasing pressure, which is central to the previous reasoning that the inner core may be composed of Fe3C.