Viscosities of hcp iron alloys under Earth’s inner core conditions  

作　　者：Yunfan Xu Yu He Shichuan Sun Wei Zhang Weiru Dai Duck Young Kim Heping Li 

机构地区：[1]Key Laboratory of High-Temperature and High-Pressure Study of the Earth's Interior,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,Guizhou,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Center for High Pressure Science and Technology Advanced Research,Shanghai 201203,China [4]Asian School of the Environment,Nanyang Technological University,50 Nanyang Avenue,Singapore 639798,Singapore [5]School of Geography and Environmental Science(School of Karst Science),Guizhou Normal University,Guiyang 550025,China

出　　处：《Geoscience Frontiers》2025年第1期383-392,共10页地学前缘(英文版)

基　　金：the support of the National Natural Science Foundation of China(42350002,42074104);the CAS Youth Interdisciplinary Team(JCTD-2022-16);the Youth Innovation Promotion Association of CAS(2020394);supported by the Guizhou Provincial 2020 Science and Technology Subsidies(No.GZ2020SIG).

摘　　要：Viscosity is critical for controlling the dynamics and evolution of the Earth’s inner core(IC).The viscosities of hexagonal close-packed(hcp)and body-centred cubic(bcc)Fe were studied experimentally and theoretically under Earth's core conditions.However,Earth’s inner core is mainly composed of Fe-Ni alloys with some light element impurities(Si,S,C,H,O),and the influence of impurities(Ni,Si,S,C,H,and O)on viscosity is still unknown.In this study,the diffusion coefficients of Fe,Ni,Si,S,C,H,and O were calculated under IC conditions using ab initio molecular dynamics(AIMD)and deep learning molecular dynamics(DPMD)methods.Among them,C,H,and O are highly diffusive like liquids in the lattice,while Fe,Ni,Si,and S diffuse through Fe site vacancies.In binary alloys,the influence of these impurities(Ni:12.5%,S:3.6%,Si:3.1%,C:1.3%,O:1.7%,H:0.4%by weight)on viscosity is insignificant.Based on the dislocation creep mechanism,the predicted viscosities of the hcp Fe alloys are 1×10^(14)-2×10^(16)Pa·s,which is consistent with the values predicted by free inner core nutation and seismic wave attenuation observations.

关 键 词：Earth’s inner core High pressure and high temperature VISCOSITY Molecular dynamics 

分 类 号：TG1[金属学及工艺—金属学]