Elastic anisotropy in hcp metals at high pressure and the sound wave anisotropy of the Earth's inner core

被引:39
作者
Antonangeli, Daniele
Merkel, Sebastien
Farber, Daniel L.
机构
[1] Lawrence Livermore Natl Lab, Energy & Environm Directorate, Livermore, CA 94550 USA
[2] Univ Sci & Technol Lille, Lab Struct & Proprietes Etat Solide, CNRS, UMR 8008, F-59655 Villeneuve Dascq, France
关键词
D O I
10.1029/2006GL028237
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
We compare the elastic anisotropy in hcp metals at high pressure obtained by radial diffraction measurements with those determined by other experiments and calculations. Our analysis demonstrates that in non-hydrostatically compressed hcp metals the assumption of a single uniform macroscopic stress applied to all grains in the polycrystal for the inversion of the lattice strain equations is violated due to plastic deformation. In addition, the derived apparent moduli and elastic anisotropy differ significantly from those derived from single crystals. We propose that for cobalt, rhenium and iron, the elastic anisotropy in the meridian plane is best described by a sigmoidal shape for the longitudinal velocity, with the fastest direction along the c-axis. Based on these results, we suggest that preferential alignment of the c-axis of iron crystallites along the Earth's rotation axis is the most plausible explanation for the observed P-wave travel time anomalies in the inner core.
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页数:5
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共 39 条
[31]   Anisotropy of the earth's inner core [J].
Song, XD .
REVIEWS OF GEOPHYSICS, 1997, 35 (03) :297-313
[32]   First-principles elastic constants for the hcp transition metals Fe, Co, and Re at high pressure [J].
Steinle-Neumann, G ;
Stixrude, L ;
Cohen, RE .
PHYSICAL REVIEW B, 1999, 60 (02) :791-799
[33]   HIGH-PRESSURE ELASTICITY OF IRON AND ANISOTROPY OF EARTHS INNER-CORE [J].
STIXRUDE, L ;
COHEN, RE .
SCIENCE, 1995, 267 (5206) :1972-1975
[34]   SUPPORT FOR ANISOTROPY OF THE EARTHS INNER-CORE FROM FREE OSCILLATIONS [J].
TROMP, J .
NATURE, 1993, 366 (6456) :678-681
[35]   The properties of iron under core conditions from first principles calculations [J].
Vocadlo, L ;
Alfè, D ;
Gillan, MJ ;
Price, GD .
PHYSICS OF THE EARTH AND PLANETARY INTERIORS, 2003, 140 (1-3) :101-125
[36]   Effect of plasticity on elastic modulus measurements [J].
Weidner, DJ ;
Li, L ;
Davis, M ;
Chen, JH .
GEOPHYSICAL RESEARCH LETTERS, 2004, 31 (06)
[37]   The plastic deformation of iron at pressures of the Earth's inner core [J].
Wenk, HR ;
Matthies, S ;
Hemley, RJ ;
Mao, HK ;
Shu, J .
NATURE, 2000, 405 (6790) :1044-1047
[38]   EVIDENCE FOR INNER CORE ANISOTROPY FROM FREE OSCILLATIONS [J].
WOODHOUSE, JH ;
GIARDINI, D ;
LI, XD .
GEOPHYSICAL RESEARCH LETTERS, 1986, 13 (13) :1549-1552
[39]   Growth model of the inner core coupled with the outer core dynamics and the resulting elastic anisotropy [J].
Yoshida, S ;
Sumita, I ;
Kumazawa, M .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 1996, 101 (B12) :28085-28103