近日，厦门大学孙阳团队研究了铁镍相图与地球内核结构。该项研究成果发表在2025年6月6日出版的《科学进展》杂志上。
铁镍合金被认为是地核的主要成分。然而，在核心条件下，人们对这种合金熔点附近的相平衡仍缺乏全面的了解，导致镍的影响尚无定论。利用从头计算模拟，研究组计算了铁镍合金在靠近内核条件下的液相和固溶体的吉布斯自由能和相图。铁镍相图为理解铁镍合金在核心条件下的先前实验观察和结晶模拟提供了至关重要的见解。
它还展示了内核结构的复杂场景，表明内核边界处的体心立方（bcc）-液体共存，以及内核内由bcc-六方密堆积（hcp）复合材料组成的多层结构的可能性。该工作阐明了镍对内核结构的实质性影响，为研究内核的成分和形成提供了额外的约束。
附：英文原文
Title: The Fe-Ni phase diagram and the Earth’s inner core structure
Author: Liangrui Wei, Zepeng Wu, Kai-Ming Ho, Renata M. Wentzcovitch, Yang Sun
Issue&Volume: 2025-06-06
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. 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 complex scenarios for inner core structures, suggesting body-centered cubic (bcc)–liquid coexistence at the inner core boundary and the possibility of multilayer structures consisting of bcc–hexagonal close-packed (hcp) composites within the inner core. Our work clarifies nickel’s substantial impact on the inner core structure, providing additional constraints for studying the core’s composition and formation.
DOI: adu1998
