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Iron-Nickel alloy in the Earth's core

Authors :
Guoyin Shen
James M. Devine
Wendy L. Mao
Jung-Fu Lin
Andrew J. Campbell
Dion L. Heinz
Source :
Geophysical Research Letters. 29:109-1
Publication Year :
2002
Publisher :
American Geophysical Union (AGU), 2002.

Abstract

[1] The phase relations of an Fe10wt%Ni alloy were investigated in a diamond anvil cell up to 86 GPa and 2382 K. Adding nickel into iron stabilizes the fcc phase to higher pressures and lower temperatures compared to pure iron, and a region of two-phase coexistence between fcc and hcp phases is observed. Iron with up to 10 wt% nickel is likely to be in the hcp structure under inner core conditions. The axial ratio (c/a) of hcp-Fe10wt%Ni has a weak pressure dependence, but it increases substantially with increasing temperature. The extrapolated c/a ratio at ∼5700 K and ∼86 GPa is approximately 1.64, lower than a theoretically predicted value of nearly 1.7 for hcp-Fe at 5700 K and inner-core pressure. A lower c/a ratio should have an effect on the longitudinal anisotropy of the hcp phase, and hence, may influence the interpretation of the seismic wave anisotropy of the inner core.

Details

ISSN :
00948276
Volume :
29
Database :
OpenAIRE
Journal :
Geophysical Research Letters
Accession number :
edsair.doi...........59d5abde7b03569399cd490e9275922d