scholarly journals Two-phase mixture of iron–nickel–silicon alloys in the Earth’s inner core

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Daijo Ikuta ◽  
Eiji Ohtani ◽  
Naohisa Hirao
Keyword(s):  
Inner Core ◽  
Earth Model ◽  
Two Phase ◽  
Silicon Alloys ◽  
Hexagonal Close Packed ◽  
Iron Nickel ◽  
Earth’S Inner Core ◽  
Phase Mixture ◽  
Core Conditions ◽  
Nickel Silicon

AbstractThe Earth’s inner core comprises iron-nickel alloys with light elements. However, there is no clarity on the phase properties of these alloys. Here we show phase relations and equations of state of iron–nickel and iron–nickel–silicon alloys up to 186 gigapascals and 3090 kelvin. An ordered derivative of the body-centred cubic structure (B2) phase was observed in these alloys. Results show that nickel and silicon influence the stability field associated with the two-phase mixture of B2 and hexagonal close-packed phases under core conditions. The two-phase mixture can give the inner core density of the preliminary reference Earth model. The compressional wave velocity of the two-phase mixture under inner core conditions is consistent with that of the preliminary reference Earth model. Therefore, a mixture of B2 and hexagonal close-packed phases may exist in the inner core and accounts for the seismological properties of the inner core such as density and velocity deficits.

scholarly journals High‐Pressure Deformation of Iron–Nickel–Silicon Alloys and Implications for Earth’s Inner Core

2021 ◽  
Vol 126 (3) ◽  
Author(s):  
Matthew C. Brennan ◽  
Rebecca A. Fischer ◽  
Samantha Couper ◽  
Lowell Miyagi ◽  
Daniele Antonangeli ◽  
...  
Keyword(s):  
High Pressure ◽  
Inner Core ◽  
Silicon Alloys ◽  
Iron Nickel ◽  
Earth’S Inner Core ◽  
Nickel Silicon

scholarly journals High-Pressure Deformation of Iron–Nickel–Silicon Alloys and Implications for Earth’s Inner Core

2020 ◽  
Author(s):  
Matthew Brennan ◽  
Rebecca Fischer ◽  
Samantha Couper ◽  
Lowell Miyagi ◽  
Daniele Antonangeli ◽  
...  
Keyword(s):  
High Pressure ◽  
Inner Core ◽  
Silicon Alloys ◽  
Iron Nickel ◽  
Earth’S Inner Core ◽  
Nickel Silicon

Anab initiostudy of S-substituted iron–nickel–silicon alloy at the Earth's inner core pressure

2008 ◽  
Vol 28 (4) ◽  
pp. 437-441 ◽  
Author(s):  
M. Mattesini ◽  
E. Buforn ◽  
A. Udías ◽  
L. Vitos ◽  
R. Ahuja
Keyword(s):  
Inner Core ◽  
Silicon Alloy ◽  
Iron Nickel ◽  
Earth’S Inner Core ◽  
Nickel Silicon

scholarly journals Two-step nucleation of the Earth’s inner core

2022 ◽  
Vol 119 (2) ◽  
pp. e2113059119
Author(s):  
Yang Sun ◽  
Feng Zhang ◽  
Mikhail I. Mendelev ◽  
Renata M. Wentzcovitch ◽  
Kai-Ming Ho
Keyword(s):  
Molecular Dynamics ◽  
Inner Core ◽  
Nucleation Mechanism ◽  
Body Centered Cubic ◽  
Hexagonal Close Packed ◽  
Key Factor ◽  
Earth’S Inner Core ◽  
Core Conditions ◽  
Dynamics Simulations ◽  
Bcc Phase

The Earth's inner core started forming when molten iron cooled below the melting point. However, the nucleation mechanism, which is a necessary step of crystallization, has not been well understood. Recent studies have found that it requires an unrealistic degree of undercooling to nucleate the stable, hexagonal, close-packed (hcp) phase of iron that is unlikely to be reached under core conditions and age. This contradiction is referred to as the inner core nucleation paradox. Using a persistent embryo method and molecular dynamics simulations, we demonstrate that the metastable, body-centered, cubic (bcc) phase of iron has a much higher nucleation rate than does the hcp phase under inner core conditions. Thus, the bcc nucleation is likely to be the first step of inner core formation, instead of direct nucleation of the hcp phase. This mechanism reduces the required undercooling of iron nucleation, which provides a key factor in solving the inner core nucleation paradox. The two-step nucleation scenario of the inner core also opens an avenue for understanding the structure and anisotropy of the present inner core.

Modeling of a two-phase system with phase change, applications in planetology: Earth's inner core and Transneptunian objects

2021 ◽  
Author(s):  
Robin Métayer ◽  
Renaud Deguen ◽  
Aurélie Guilbert-Lepoutre ◽  
Marine Lasbleis ◽  
Jenny Wong
Keyword(s):  
Phase Change ◽  
Inner Core ◽  
Phase System ◽  
Two Phase ◽  
Transneptunian Objects ◽  
Earth’S Inner Core

Measuring the melting curve of iron at super-Earth core conditions

Science ◽  
2022 ◽  
Vol 375 (6577) ◽  
pp. 202-205
Author(s):  
Richard G. Kraus ◽  
Russell J. Hemley ◽  
Suzanne J. Ali ◽  
Jonathan L. Belof ◽  
Lorin X. Benedict ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Inner Core ◽  
Melting Curve ◽  
Radiation Shielding ◽  
Metal Core ◽  
Earth Core ◽  
Core Boundary ◽  
Earth Like Planets ◽  
Earth’S Inner Core ◽  
Core Conditions

Terapascal iron-melting temperature The pressure and temperature conditions at which iron melts are important for terrestrial planets because they determine the size of the liquid metal core, an important factor for understanding the potential for generating a radiation-shielding magnetic field. Kraus et al . used laser-driven shock to determine the iron-melt curve up to a pressure of 1000 gigapascals (see the Perspective by Zhang and Lin). This value is about three times that of the Earth’s inner core boundary. The authors found that the liquid metal core lasted the longest for Earth-like planets four to six times larger in mass than the Earth. —BG

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