In recent decades,global seismic observations have identified increasingly complex anisotropy of the Earth’s inner core.Numerous seismic studies have confirmed hemispherical variations in the inner core’s anisotropy...In recent decades,global seismic observations have identified increasingly complex anisotropy of the Earth’s inner core.Numerous seismic studies have confirmed hemispherical variations in the inner core’s anisotropy.Here,based on ab initio molecular dynamics calculations,we report how the anisotropy of hexagonal close-packed(hcp)-iron,under inner core conditions,could be altered when alloyed with light elements.We find that light elements in binary allows with iron-hcp-Fe-X(X=C,O,Si,and S)-could have significant effects on density,sound velocities,and anisotropy,compared with the behavior of pure hcp-iron;the anisotropy of these binary alloys depends on combined effects of temperature and the particular alloying light element.Furthermore,the change in anisotropy strength with increasing temperature can be charted for each alloy.Alloying pure iron with some light elements such as C or O actually does not increase but decreases core anisotropy at high temperatures.But the light element S can significantly enhance the elastic anisotropy strength of hcp-Fe.展开更多
The effects of light elements on the elastic properties of disordered binary hcp-Fe alloys were investigated at high pressures using plane-wave density functional theory combined with the Monte Carlo special quasi-ran...The effects of light elements on the elastic properties of disordered binary hcp-Fe alloys were investigated at high pressures using plane-wave density functional theory combined with the Monte Carlo special quasi-random structure method.We found that the increase in the O content in hcp-Fe had a more pronounced effect on the sound velocity than Si,S,and C.The longitudinal wave velocity was decreased by∼6%with 2%O content,which was a much greater decrease than the values of 0.6%and 2%induced by the same content of Si and S,respectively,under high pressures.Compared with the other three light elements,the longitudinal wave velocity of the Fe-C alloy exhibited the most gradual decreasing with increasing C content.In addition,the effects of different O and S contents on the anisotropy of hcp-Fe alloys strongly depended on the variation in pressure,whereas the pressure only slightly affected the anisotropy of Fe-Si alloy systems.展开更多
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.41704088 and 11804284)the Open Foundation of Hypervelocity Impact Research Center of CARDC(Grant No.20200202)。
文摘In recent decades,global seismic observations have identified increasingly complex anisotropy of the Earth’s inner core.Numerous seismic studies have confirmed hemispherical variations in the inner core’s anisotropy.Here,based on ab initio molecular dynamics calculations,we report how the anisotropy of hexagonal close-packed(hcp)-iron,under inner core conditions,could be altered when alloyed with light elements.We find that light elements in binary allows with iron-hcp-Fe-X(X=C,O,Si,and S)-could have significant effects on density,sound velocities,and anisotropy,compared with the behavior of pure hcp-iron;the anisotropy of these binary alloys depends on combined effects of temperature and the particular alloying light element.Furthermore,the change in anisotropy strength with increasing temperature can be charted for each alloy.Alloying pure iron with some light elements such as C or O actually does not increase but decreases core anisotropy at high temperatures.But the light element S can significantly enhance the elastic anisotropy strength of hcp-Fe.
基金supported by the Natural Science Foundation of Sichuan Province(2022NSFSC1826,2022NSFSC1243).
文摘The effects of light elements on the elastic properties of disordered binary hcp-Fe alloys were investigated at high pressures using plane-wave density functional theory combined with the Monte Carlo special quasi-random structure method.We found that the increase in the O content in hcp-Fe had a more pronounced effect on the sound velocity than Si,S,and C.The longitudinal wave velocity was decreased by∼6%with 2%O content,which was a much greater decrease than the values of 0.6%and 2%induced by the same content of Si and S,respectively,under high pressures.Compared with the other three light elements,the longitudinal wave velocity of the Fe-C alloy exhibited the most gradual decreasing with increasing C content.In addition,the effects of different O and S contents on the anisotropy of hcp-Fe alloys strongly depended on the variation in pressure,whereas the pressure only slightly affected the anisotropy of Fe-Si alloy systems.
