Melting and phase relations of Fe-Ni-Si determined by a multi-technique approach
Melting and phase relations of Fe-Ni-Si determined by a multi-technique approach
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DOI：
10.1016/j.epsl.2021.117358
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发表时间：
2022-03-17
影响因子：
5.3
通讯作者：
Jackson, Jennifer M.
中科院分区：
文献类型：
--
作者：
Dobrosavljevic, Vasilije V.;Zhang, Dongzhou;Jackson, Jennifer M.
许多研究表明，硅是地球和水星核心的候选轻元素。然而，硅对核心材料的熔化温度和核心的热分布的影响知之甚少，由于熔体检测技术之间的分歧，加热过程中样品压力演变的不确定性，以及调查镍和硅对铁相图的综合影响的研究稀少。在这项研究中，我们开发了一种多技术方法来测量铁合金的高压熔化和固相关系，并将其应用于Fe0.8Ni0.1Si0.1（Fe-11wt%Ni-5.3wt%Si），这是一种与最近估计的地球和水星核心相一致的成分。这种方法结合了两种原子级技术的结果（20-83 GPa）：同步穆斯堡尔谱（SMS）和同步X射线衍射（XRD）。熔化是独立检测的穆斯堡尔信号的损失，专门由固体结合的铁核，和液体的扩散X射线散射信号的发病。使用突发加热和背景更新方法来量化加热过程中参考背景的变化，有助于确定液体扩散信号起始，并导致通过两种技术分别确定的熔解温度具有很强的再现性和极好的一致性。XRD测量还限制了hcp-fcc相界和加热过程中样品的原位压力演化。我们将我们更新的热压模型应用于已发表的fcc-Fe和fcc-Fe 0. 9 Ni 0.1的SMS熔化数据，以精确评估硅对熔化温度的影响。我们发现，添加10摩尔%的Si到Fe 0.9Ni 0.1中，在低压（< 60 GPa）下使熔化温度降低了约250 K，并消除了hcp-fcc相界。外推我们的结果，我们限制的hcp-fcc-液体准三相点的位置在147 +/- 14 GPa和3140 +/- 90 K，这意味着500 K的熔化温度降低相比，Fe0.9Ni0.1。结果表明，在极端条件下熔化的调查相结合的互补实验技术的优势。(c)2021爱思唯尔有限公司版权所有。
Many studies have suggested silicon as a candidate light element for the cores of Earth and Mercury. However, the effect of silicon on the melting temperatures of core materials and thermal profiles of cores is poorly understood, due to disagreements among melt detection techniques, uncertainties in sample pressure evolution during heating, and sparsity of studies investigating the combined effects of nickel and silicon on the phase diagram of iron. In this study we develop a multi-technique approach for measuring the high-pressure melting and solid phase relations of iron alloys and apply it to Fe0.8Ni0.1Si0.1 (Fe-11wt%Ni-5.3wt%Si), a composition compatible with recent estimates for the cores of Earth and Mercury. This approach combines results (20-83 GPa) from two atomic-level techniques: synchrotron Mossbauer spectroscopy (SMS) and synchrotron x-ray diffraction (XRD). Melting is independently detected by the loss of the Mossbauer signal, produced exclusively by solid-bound iron nuclei, and the onset of a liquid diffuse x-ray scattering signal. The use of a burst heating and background updating method for quantifying changes in the reference background during heating facilitates the determination of liquid diffuse signal onsets and leads to strong reproducibility and excellent agreement in melting temperatures determined separately by the two techniques. XRD measurements additionally constrain the hcp-fcc phase boundary and in-situ pressure evolution of the samples during heating. We apply our updated thermal pressure model to published SMS melting data on fcc-Fe and fcc-Fe0.9Ni0.1 to precisely evaluate the effect of silicon on melting temperatures. We find that the addition of 10 mol% Si to Fe0.9Ni0.1 reduces melting temperatures by similar to 250 K at low pressures (< 60 GPa) and flattens the hcp-fcc phase boundary. Extrapolating our results, we constrain the location of the hcp-fcc-liquid quasi-triple point at 147 +/- 14 GPa and 3140 +/- 90 K, which implies a melting temperature reduction of 500 K compared with Fe0.9Ni0.1. The results demonstrate the advantages of combining complementary experimental techniques in investigations of melting under extreme conditions. (c) 2021 Elsevier B.V. All rights reserved.