Phase diagrams of Fe–Si alloys at 3–5 GPa from electrical resistivity measurements

IF 1.2 4区地球科学 Q4 MATERIALS SCIENCE, MULTIDISCIPLINARY

Physics and Chemistry of Minerals Pub Date : 2022-10-27 DOI:10.1007/s00269-022-01220-7

Meryem Berrada, Richard A. Secco

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Abstract

One of the most extensively investigated properties of Fe is electrical resistivity (ρ) which features several well-established temperature (T) dependent characteristics. Based on systematic data for Fe and Fe–Si alloys and guidance from the 1 atm diagram, the T-X (composition X) phase diagram can be obtained at constant pressure (P) by plotting maps of constant ρ contours, proposed herein to be called ‘iso-ohms’, maps of constant δρ/δT, as well as maps of variations of exponent x in power law fits to ρ(T^x). Electrical resistivity measurements of Fe-(≤ 17wt%)Si alloys are available at 3–5 GPa and up to liquid temperatures. This study provides a new approach to mapping high P–T structural phase diagrams in the Fe-rich region of the Fe–Si system at moderate pressures and may be used for other compositions. Maps of iso-ohms suggest the α phase is the less resistive phase followed by α₂, α₁, η + α₁, and ε + α₁. Above ~ 11 wt% Si, the ε + α₁ displays a higher ρ than the liquid phase. This is discussed in terms of s and d electron scattering. Maps of constant δρ/δT emphasize the magnetic transition and boundary between the ε + α₁ and η + α₁ phases, while variations of exponent x outline the α₂ region. The Fe–Si system is of interest to the cores of the moon and Mercury.

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由电阻率测量得到的3-5 GPa Fe-Si合金相图

铁最广泛研究的性质之一是电阻率(ρ)，它具有几个公认的温度(T)依赖特性。根据Fe和Fe - si合金的系统数据和1atm图的指导，可以通过绘制恒定ρ等值线图(本文提出的“等欧姆”)，恒定δρ/δT的线图以及幂律中指数X的变化图拟合ρ(Tx)，得到定压(P)下的T-X(成分X)相图。Fe-(≤17wt%)Si合金的电阻率测量可在3-5 GPa和高达液体温度下使用。该研究为在中等压力下绘制Fe-Si体系富铁区域的高P-T结构相图提供了一种新的方法，并可用于其他成分。等欧姆图显示，α相是电阻较小的相，其次是α2、α1、η + α1和ε + α1。在~ 11wt % Si以上，ε + α1的ρ值高于液相。这是根据s和d电子散射来讨论的。常数δρ/δT图强调ε + α1和η + α1相之间的磁跃迁和边界，而指数x的变化则勾勒出α2区。月球和水星的核心对铁-硅体系很感兴趣。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Physics and Chemistry of Minerals 地学-材料科学：综合

CiteScore

2.90

自引率

14.30%

发文量

审稿时长

3 months

期刊介绍： Physics and Chemistry of Minerals is an international journal devoted to publishing articles and short communications of physical or chemical studies on minerals or solids related to minerals. The aim of the journal is to support competent interdisciplinary work in mineralogy and physics or chemistry. Particular emphasis is placed on applications of modern techniques or new theories and models to interpret atomic structures and physical or chemical properties of minerals. Some subjects of interest are: -Relationships between atomic structure and crystalline state (structures of various states, crystal energies, crystal growth, thermodynamic studies, phase transformations, solid solution, exsolution phenomena, etc.) -General solid state spectroscopy (ultraviolet, visible, infrared, Raman, ESCA, luminescence, X-ray, electron paramagnetic resonance, nuclear magnetic resonance, gamma ray resonance, etc.) -Experimental and theoretical analysis of chemical bonding in minerals (application of crystal field, molecular orbital, band theories, etc.) -Physical properties (magnetic, mechanical, electric, optical, thermodynamic, etc.) -Relations between thermal expansion, compressibility, elastic constants, and fundamental properties of atomic structure, particularly as applied to geophysical problems -Electron microscopy in support of physical and chemical studies -Computational methods in the study of the structure and properties of minerals -Mineral surfaces (experimental methods, structure and properties)