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Low temperature diffusion coefficients in the Fe-Ni and FeNiP systems: Application to meteorite cooling ratesThe interdiffusion coefficient of FeNi in fcc taenite (gamma) of Fe-Ni and Fe-Ni-0.2 P alloys was measured as a function of temperature between 600 and 900 C. This temperature range is directly applicable to the nucleation and growth of the Widmanstatten pattern in iron meteorites and metal regions of stony and stony-iron meteorites. Diffusion couples were made from FeNi or FeNiP alloys which ensured that the couples were in the taenite phase at the diffusion temperature. The presence or absence of grain boundary diffusion was determined by measuring the Ni profile normal to the existing grain boundaries with the AEM. Ignoring any variation of interdiffusion coefficient with composition, the measured data was plotted versus the reciprocal of the diffusion temperature. The FeNi data generally follow the extrapolated Goldstein, et al. (1965) data from high temperatures. The FeNiP data indicates that small additions of P (0.2 wt%) cause a 3 to 10 fold increase in the FeNi interdifussion coefficient increasing with decreasing temperature. This increase is about the same as that predicted by Narayan and Goldstein (1983) at the Widmanstatten growth temperature.
Document ID
19850007317
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Dean, D. C.
(Lehigh Univ. Bethlehem, PA, United States)
Goldstein, J. I.
(Lehigh Univ. Bethlehem, PA, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1984
Publication Information
Publication: Lunar and Planetary Institute The 47th Ann. Meteoritical Soc. Meeting
Subject Category
Lunar And Planetary Exploration
Accession Number
85N15626
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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