HR: 1340h
AN: MR23A-0047    [Abstracts]
TI: Phase relations of Fe-Ni alloys at high pressure and temperature
AU: * Heinz, D L
EM: heinz@uchicago.edu
AF: Department of the Geophysical Sciences, University of Chicaqgo, Chicago, IL 60637 United States
AU: * Heinz, D L
EM: heinz@uchicago.edu
AF: James Franck Institute, University of Chicago, Chicago, IL 60637 United States
AU: Mao, W
EM: wmao@uchicago.edu
AF: Department of the Geophysical Sciences, University of Chicaqgo, Chicago, IL 60637 United States
AU: Mao, W
EM: wmao@uchicago.edu
AF: Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015 United States
AU: Campbell, A J
EM: ajc@umd.edu
AF: Department of the Geophysical Sciences, University of Chicaqgo, Chicago, IL 60637 United States
AU: Campbell, A J
EM: ajc@umd.edu
AF: Chicago Center for Cosmochemistry, University of Chicago, Chicago, IL 60637 United States
AU: Shen, G
EM: shen@cars.uchicago.edu
AF: Consortium for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637 United States
AB: Using a diamond anvil cell and double-sided laser-heating coupled with synchrotron x-ray diffraction, we determined phase relations for three compositions of Fe-rich FeNi alloys in situ at high pressure and high temperature. We studied Fe with 5 wt%, 15 wt%, and 20 wt% Ni to 55 GPa, 62 GPa, and 72 GPa respectively at temperatures up to ~3000 K. Ni stabilizes the face centered cubic phase to lower temperatures and higher pressure, and this effect increases with increasing pressure. Extrapolation of our experimental results suggests that the stable phase at inner core conditions is hexagonal close packed, although if the temperature at the inner core boundary is higher than ~6400 K, a two phase outer region may also exist. Comparison to previous laser-heated diamond anvil cell studies demonstrates the importance of kinetics even at high temperatures.
DE: 3909 Elasticity and anelasticity
DE: 3924 High-pressure behavior
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005