The Fe-Ni phase diagram and the Earth's inner core structure

Abstract

The Fe-Ni alloy is believed to be the main component of Earth's core. Yet, a comprehensive understanding of phase equilibria near the melting point of this alloy under core conditions is still lacking, leaving the effect of nickel inconclusive. Using ab initio simulations, we computed Gibbs free energy and phase diagram for liquid and solid solutions of the Fe-Ni alloy under conditions close to the inner core, considering inner-shell electron contributions and non-ideal mixing effects. The Fe-Ni phase diagram provides crucial insights for understanding previous experimental observations and crystallization simulations of the Fe-Ni alloy under core conditions. It also presents new scenarios for inner core structures, suggesting bcc-liquid coexistence at the inner core boundary and the possibility of multi-layer structures consisting of bcc-hcp composites within the inner core. Our work clarifies nickel's substantial impact on the inner core structure, providing new constraints for the study of core's composition and formation.

References in corpus (8)

• The Effect of Lattice Vibrations on Substitutional Alloy Thermodynamics
• A scalable parallel Monte Carlo algorithm for atomistic simulations of precipitation in alloys
• Iron under Earth's core conditions: Liquid-state thermodynamics and high-pressure melting curve
• Hybrid Monte Carlo/molecular dynamics simulation of a refractory metal high entropy alloy
• Anomalous compressibility of ferropericlase throughout the iron spin crossover
• Ab initio melting temperatures of bcc and hcp iron under the Earth's inner core condition
• Deep-learning-based prediction of the tetragonal$\to$cubic transition in davemaoite
• Melting Temperature of Iron Under the Earth's Inner Core Condition from Deep Machine Learning

Cited by in corpus (2)

• Ab initio superionic-liquid phase diagram of Fe1-xOx under Earth's inner core conditions
• Incorporating Gibbs free energy into interatomic potential fitting