Experimental study and thermodynamic calculations of phase relations in the Fe-C system at high pressure
Experimental study and thermodynamic calculations of phase relations in the Fe-C system at high pressure
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DOI：
10.1016/j.epsl.2014.09.044
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发表时间：
2014-12-15
影响因子：
5.3
通讯作者：
Brosh, Eli
中科院分区：
文献类型：
--
作者：
Fei, Yingwei;Brosh, Eli
我们在1473-2073 K温度范围内进行了一系列压力高达25 GPa的Fe-C系熔化实验。结果定义了在几个压力下的相关系，包括共晶温度和组成作为压力的函数，固体铁和液体之间的碳分配，以及涉及碳化铁的熔化关系的变化。为了在较宽的压力和温度范围内对相关系进行内插和外推，我们建立了Fe-C二元系的综合热力学模型。在5，10和20 GPa的压力下计算的相图再现实验数据，包括碳在固体铁中的溶解度和压力对共晶温度和组成的影响。在5 GPa以上的压力下，Fe_7 C_3的形成被正确地模拟，并在5和10 GPa之间的Fe-C系统中的相关系的变化被捕获在模型中。该模型提供了在136 GPa和330 GPa的相关系的预测，在较低的压力下的系统的热化学的现有知识的基础上。计算的相关系可用于了解内芯结晶过程中碳的作用，预测内芯和外芯之间的碳分布以及固体内芯的矿物学。(C)2014爱思唯尔有限公司版权所有。
We have conducted a series of melting experiments in the Fe-C system at pressures up to 25 GPa in the temperature range of 1473-2073 K. The results define the phase relations at several pressures, including the eutectic temperature and composition as a function of pressure, carbon partitioning between solid iron and liquid, and change of melting relations involving iron carbides. In order to interpolate and extrapolate the phase relations over a wide pressure and temperature range, we have established a comprehensive thermodynamic model in the Fe-C binary system. The calculated phase diagrams at pressures of 5, 10, and 20 GPa reproduce the experimental data, including the solubility of carbon in solid iron and the effect of pressure on the eutectic temperature and composition. The formation of Fe7C3 at pressures above 5 GPa is correctly modeled and the change of phase relations in the Fe-C system between 5 and 10 GPa is captured in the model. The model provides predictions of the phase relations at 136 GPa and 330 GPa, based on existing knowledge of the thermochemistry of the system at lower pressure. The calculated phase relations can be used to understand the role of carbon during inner core crystallization, predicting carbon distribution between the inner and outer cores and mineralogy of the solid inner core. (C) 2014 Elsevier B.V. All rights reserved.