The elastic properties of hcp-Fe alloys under the conditions of the Earth's inner core
The elastic properties of hcp-Fe alloys under the conditions of the Earth's inner core
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DOI：
10.1016/j.epsl.2018.04.013
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发表时间：
2018-07-01
影响因子：
5.3
通讯作者：
Brodholt, John P.
中科院分区：
文献类型：
--
作者：
Li, Yunguo;Vocadlo, Lidunka;Brodholt, John P.
地球物理和宇宙化学的限制表明，内核主要由铁组成，并含有少量轻元素。然而，尽管经过多年的广泛研究，还没有发现单一的合金化轻元素能够同时匹配观测到的内核密度和两种地震速度。这引发了许多关于降低速度的其他机制的建议，如无弹性或预熔化。然而，一种尚未探索的可能性是，两种或两种以上轻元素的组合可能会在内核的速度和密度方面产生所需的降低。为了验证这一点，我们用从头算分子动力学计算方法，绘制了S、硅和碳合金化的HCP-Fe合金在360 Gpa到熔化温度的弹性性质空间。基于混合固溶体模型和对三元系的直接模拟，我们发现了一些能够与观测到的内核性质相匹配的组分。这是首次将核芯的密度、V-p、V-S和泊松比与HCP-Fe合金直接匹配。(C)2018年提交人(S)。爱思唯尔出版公司(Elsevier B.V.)
Geophysical and cosmochemical constraints suggest the inner-core is mainly composed of iron with a few percent of light elements. However, despite extensive studies over many years, no single alloying light-element has been found that is able to simultaneously match the observed inner-core density and both seismic velocities. This has motivated a number of suggestions of other mechanism to lower velocities, such as anelasticity or premelting. However, an unexplored possibility is that a combination of two or more light-elements might produce the desired reduction in velocities and densities of the inner core. In order to test this, we use ab initio molecular dynamics calculations to map the elastic property space of hcp-Fe alloyed with S, Si and C at 360 GPa up to the melting temperature. Based on a mixing solid solution model together with direct simulations on the ternaries, we found a number of compositions which are able to match the observed properties of the inner core. This is the first time that the density, V-p, V-s and the Poisson's ratio of the inner core have been matched directly with an hcp-Fe alloy. (C) 2018 The Author(s). Published by Elsevier B.V.