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Iron‐Nickel alloy in the Earth's core
Author(s) -
Lin JungFu,
Heinz Dion L.,
Campbell Andrew J.,
Devine James M.,
Mao Wendy L.,
Shen Guoyin
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl015089
Subject(s) - inner core , alloy , nickel , materials science , anisotropy , phase (matter) , diamond anvil cell , core (optical fiber) , diamond , analytical chemistry (journal) , metallurgy , thermodynamics , high pressure , chemistry , composite material , optics , physics , organic chemistry , chromatography
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.